Hard cold start,have to warm uyp till thermo hits 80 centegrade,if not allowed to warm up,car bucks allot lookese power struggle to even idle up,the exhaust was turning cherry red last night after i drove it,it would not shift from 4,000 rpm,the eha is causing all this i think i was disconnected when purchased,and runs great while unplugged,but needs to be plugged in for winter or it will not start,got any ideas?

no car told maker or model or engine size.
there are lots causes that, hard starts
if spark good and strong and even HV spark wire sets fresh.
the short list.

1. bad fuel
2. too much fuel cranked and floods
3. IAC bad, idle air valve stuck and wants to flood cold.
4. cold idle is the big clue, where too low. IAC failing
5. EGR sticking open at idle. possible.
6. if you press gas Pedal, at 5% (about) and starts easy and likes that until it worms up that means the IAC is dead.
7. I stop here lots more, no car told.

all cars modern EFI is it EFI> have IAC and ISC valves 1 or both.
and if stuck idle fails. hot or cold.
no car told why post like that 100 year of cars and 10,000 engines.
????

Sounds like the M.A.F. sensor. It monitors the air temp before it goes into the engine like example, if its cold out,it tell the p.c.m to adjust the air,fuel mixture because it need a little more gas to start and run a cold engine compared to it be 80 degrees out and the engine needing less gas to run. I try to explain it the best way that I can but it sounds like to me you have a bad MAF sensor.the usually located in the breather box by the air filter or in the inlet tube before it goes into the intake. Good luck,stay safe and keep us posted!

I would start the IAC.
Idle air control valve.
Then take the rubber intake off and clean with a lint free rag sprayed with carb/choke cleaner, the intake and butterfly.
I'm taking you referring to having to hold your foot you mean it starts but dies unless you hold the throttle until it warms up?

I had a problem with both the speedometer and odometer in a Lincoln. It may also have an effect on the engine operation. My speedometer showed 45mph standing still and miles were rolling up on the odometer.

For me, it was a bad Alternator. The alternator was shorting out through the case. You should have your alternator checked and if you find out it is good, then the problem is something that is charging the car body.

You are getting a stray current that is messing up your dash and engine controls. You may have a power wire which rubbed through its insulation.

The idle is generally higher along w the fuel consumption when cold. Poss coolant sensor,, all sensors work together to adjust idle & adjust air/fuel mixture. A bad thermos would give u other symptoms too, {bad heating/ AC) Good luck scan it 1st & have all the SENSORS READING READ & ck for codes.

on a cold start car will idle fast till it warms up then will drop to about 1000 rpm, try increacing idle speed so when it warms and drops it should stay idleing

It could be the cold start valve is staying on. I would also check the thermo-time switch. Check the cold start valve for power after the car is warmed up.

replace main relay

1.Start by changing plugs and wires. 2.Check for vacuum leaks. With the engine running, wigglr every hose you can see, to make sure nothing is loose or cracked. 3.Change fuel filter. 4.Check timing. 5.Check air control valve. 6.Check idle control sensor.

I need to get a clear mental picture of what exactly is happening.

With this said, you stated that the car "runs fine" until warmed up.

Q: When you start the car when cold it idles fine?
Q: If you allow the car to idle until "fully" warmed does the car stall?
Q: As the car begins to warm up, Does the RPM fluctuate abnormally?
Q: Does the car Only stall when you press on the gas pedal or does it stall just sitting and idling in addition to pressing the gas pedal?
Q: If you can drive it while cold does the car stall during acceleration when warm or only at Stop Signs / Lights?
Q: If you wait 20min or so, can you start the car again?
Q: How many miles are on the car?