I have an 87 ford bronco with a 5.0 when i unplug

Bucking Bronco (unpredicatable stalling) - 80-96 Ford ...

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Jan 7, 2011 - 20 posts - ‎5 authors Page 1 of 4 - Bucking Bronco (unpredicatable stalling) - posted in 80-96 Ford BroncoTech Support: I have a 1996 Bronco. ... BUT, on the way home today--about 25 miles into the trip, it started again. ...... F4PZ-9155-B Kit BB - 1990/91 5.0L/5.8L/7.5L (allwheel bases except 137" WB and 161" WB) AG $ ...

Tests/Procedures: 1. Unplug the mass air flow sensor and see if the concern is gone or improved. If so, suspect mass air flow sensor or circuit problem.

2. Unplug the alternator and see if concern is gone, if so, suspect the alternator or its circuits.

3. Unplug the camshaft position sensor and see if concern is gone, if so, suspect cam sensor/synchronizer fault or incorrectly installed synchronizer.

4. Unplug the DPFE sensor and see if concern is resolved, if so, suspect shorted DPFE sensor.

5. Check torque converter command during concern, make sure it is not being commanded on during surge.

6. Use lab scope to check crankshaft position signal during concern and ensure the signal is not dropping off.

David,
DTC 3-4 at idle means the EVP voltage is above the closed limit.
Translation: The EVP sensor (EGR valve position) is unplugged or the wiring between it and the computer has an open. The EVP sensor has a 3-wire plug on it, and you can find the EVP on top of the EGR valve (that's the metal mushroom between the intake and a pipe coming from the driver side exhaust manifold (on a v-8)).
It's also possible that the EVP sensor is bad (open).
Good luck.
Mike M, 35-year Phord Phixer

plugged or bad catalytic converter, when my car surged while driving or at a stop it was a bad EGR Valve

EGR POSITION SENSOR CIRCUIT HIGH.
Possidle Causes:
(K34) EGR POSITION SENSOR SIGNAL CIRCUIT SHORTED TO (F857) 5-VOLT SUPPLY CIRCUIT.
(K34) EGR POSITION SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE.
(K34) EGR POSITION SENSOR SIGNAL CIRCUIT OPEN.
SENSOR GROUND CIRCUIT OPEN.
EGR SOLENOID ASSEMBLY.
PCM.

Check the spark with an inductive timing light, and check the fuel system by trying some starting fluid.
Try a smaller spark plug gap, like .028".
Need to check the sensors, like temperature, throttle position, O2, cam position, knock, etc.
Check for operation of purge, PVC, and EGR valves, that can effect mixture and make starting hard.

Check and see if the egr is stuck open at idle. It should have ported vacuum on egr valve. If egr is not stuck open, Check throttle position sensor, and map sensor for proper operation. Also check throttle plate for carbon buildup

check the Wiper motor and the switch. go over all the fuses in the fuse box as well. everything is well linked together. have someone check the wiper relay (which may be on the fuse block).

The problem is most likly the sending unit in the fuel tank but check the float. drain tank, there are two bolt in the straps on the fuel tank lossen enuf to lower tank to get to top to unplug wires and fuel lines once tank is on the ground thee is a ring on the top of tank holding the pump and sending unit in tap ring around with a screw driver to lossen once you have that off just pull unit out of tank and follow directions that come with sending unit. reverse removal procedure. good luck.

have the egr valve checked