91 corvette-starts and idles but when you give throttle it chokes out? replaced tps,fuel pump cleaned lines replaced fuel pump relay,, fuel pressure is 39lbs, replaced dist .cap,module, coil, rotor and egr.no codes are shown

Yea , those crossfire injection vettes can be a bear sometimes . I had dealings with them 84-85 - 86 working as a tech at a chevy dealer . Don't remember much about them , haven't heard anything about them for long time .

How's the fuel pressure ? Have you put a fuel gauge on it ? I would imagine you don't have a Tech 1 scan tool ? What's the map sensor voltage at idle ?

1984 Corvette hesitation stalling stumbling During Warm Up Only

1984 Corvette cleaning checking the check valves

I assume you are not getting fuel spray from the injectors ?
If you are getting voltage to the injectors you should be able to ground and get a spray. If no spray, they may be stopped up from sitting.

Fuel injectors cleaning ! How to Diagnose Test and Clean Dirty Clogged or Bad Fuel Injectors

I can think of four things. Do each in turn and test the engine after completing each one. If it gets fixed early in the list avoid the items later on. 1) check that your throttle interior is clean 'like new' along with the idle air control valve.
2) Idle Air Control Valve IACV - How to check? Physically remove the IACV but keep the electrical connection to it and loosely blank off the ports to the throttle inlet assembly, exposed by the IACV removal. Turn the engine on and examine the IACV valve movement in response to additional loads (power steering inputs etc). The valve should open and close according to demand causing perceptible change in engine speed with increased power demand being made on the engine.

The electrical connector to the IACV can have 2 or 4 pins:-

2 pins: resistance between pins should about 10 OHMS +/- 3 OHMS. Resistance between either of the pins and the valve body is greater than 10,000 OHMS

4 pins: resistance between diagonally positioned pins should be about 20 OHMS
How to fix? If the motor of the IACV has failed then replace it. If the valve is gummed closed by baked oil and carbon then clean it thoroughly with carburetor choke cleaner spray and a cloth. Similarly if the entry and exit ports on the throttle body to the IACV look blocked again clean them out thoroughly
3) Throttle Position Sensor TPS - How to check? The socket for electrical connection with the TPS has 3 pins, one for 'ground', one for 5 volts 'reference' and a third (generally the middle one) for 'signal' output. Back probe the signal pin in the connector to the TPS. Attach the positive lead of a voltmeter to the probe and measure the voltage output as the throttle plate is rotated. If working correctly the meter should show a voltage consistent with the throttle position from approximately 1 volt when closed and 5 volts when fully open. What is looked for is smooth voltage increase with throttle change. If there are drop outs in the transition or that there is no transition seen the TPS is faulty.

How to fix? If the track is dirty causing drop outs, try cleaning it with residue-free electrical cleaning spray. If the track is worn it is perhaps easiest to replace the complete device. In some instances it may be possible to adjust the location of the central mount of the TPS contact arm along the throttle shaft by a few millimeters and in the process cause a fresh concentric region of

4) Fuel pressure regulator _ Yes I know you have checked it for pressure but at start up when the ignition is at position 2 the fuel pump starts up and pressurizes the fuel rail. As you turn to position 3 "ignition" power is cut to the pump and fuel pressure is maintained by a non-return valve in the pump. If that valve is faulty the fuel pressure in the rail will drop to zero just when you need it and no fuel can be injected. Check the fuel pressure when at position 2 and then switched off; fuel pressure should be maintained for up to 5 minutes with little or no loss. If there is pressure loss then either the non-return valve is faulty or you have leak in the fuel pressure regulator. If it is such a leak, fuel will dribble from the vacuum line connected to it when disconnected.

You need to check the fuel pressure to the throttle body. If the fuel pump is nearly worn out, it will display similar symptoms. Did you read out any codes on the computer before starting this repair? Good luck!

replace the faulty fuel pump relay next to get you going back to normal

replace the coolant temp sensor, not the coolant temp sending unit

I HAVE PERSONALLY CHANGED A FEW THROTTLE POSITON SENSORS IN THESE VEHICLES. BUT BEFORE YOU DO THAT, TRY SPRAYING SOME CARB AND CHOKE SPRAY IN THE THROTTLE BODY WHILE THE CAR IS RUNNING. YOU MAY HAVE TO HOLD IT AT A HIGH IDLE SO IT DOESN'T DIE ON YOU. THIS SHOULD HELP TO REMOVE THE CARBON IN THE THROTTLE BODY. IF IT STILL WANTS TO CHOKE, THEN CHANGE THE T.P.S. HOPE THIS HELPS. PLEASE KEEP ME POSTED. THANKS FOR AN HONEST RATING AND FOR USING FIX-YA. GOOD LUCK

Try clamping the fuel return line with the appropriate tool that wont damage line and see if it improves if so you need a fuel pump or pressure relief valve.I know you said you had fuel pressure but you took that reading while vehicle was idleing so you cant check for pressure in above idle conditions.Is your air cleaner assembly as original with no holes or leaks from air box to throttle body?Its more likely to be a mass air flow meter.This problem occured to my vette while i was on holiday there.cost$89 exchange.good luck

poss. is fuel pressure reg. problem. put a guage on the test port and check press. should be above 35psi. see if it stays running when you spray choke cleaner in the pcv valve steadily while starting. if the engine stays running after a few seconds of running on choke cleaner then probably a bad fuel pump relay cause the oil pressure switch will keep the pump on without the relay when it has good oil pressure.
let me know if ya can do this or if it helps.