Car stalls when hot. Running out of things to test

[Killacortes]

Hey guys, im pretty stumped on this problem im having and would like any feedback on what i else i could check.

Background-
-1989 325i
-stock eta bottom end
-bimmerheads dual pattern turbo cam
-welded middle coolant passeges (this head was bought from a P.O)
-VAC dual valve springs
-HD rockers/new eccentrics


Problem-
-Car stalls when warm, specifically when the coolant temp sensor gets warm.
-with a different sensor plugged in outside the thermostat housing the car wont stall. but as soon as i hold a lighter to it to simulate operating temps the car stalls.
-stumbles when pressing the throttle quickly
-stalls when rpm's get too low, but stays running if i hold the throttle above 1k
-no problems from stomp test (code 1444)
-gauge cluster goes to 0rpm then to 800rpm when i turn it off and take out the key


What's been tested/done
-swapped wiring harness
-vacuum leaks fixed. Smoke tested/New gaskets top to bottom
-swapped ecu
-new cap, rotor, cps
-fuel pump holds pressure even when it stalls (~42psi min)
-alternator replaced
-new coolant temp sensor
-swapped ICV and AFM
-swapped injectors and FPR
-swapped o2 sensor
-swapped coil
-new plugs
-swapped trigger wheel
-swapped intake manifold
-replaced ground straps


ill be updating the list as i test out more things.

[Bmw679]

Check fuses, relays.

My car eta did the same thing, I swapped m20b25 and it runs like a champ now. Also try bleeding the cooling system.

[Killacortes]

Thanks for the suggestions. The fuses and relays all check out and the bleeding system is bled and does not overheat.

[Bmw679]

check engine harness. Do you have front battery location or trunk? Could be the ground on there.

[Killacortes]

Battery is in the trunk. Harness was the first thing we swapped and the grounds are new. Even tried to add an extra ground at one point but it did nothing

[MrBurgundy]

check the fpr.

[Killacortes]

Fpr was swapped with a known working one and holds pressure steady at 42psi. The issue starts only when the coolant temp sensor gets hot. We also did a lighter test to the sensor to confirm that the car stalls once the temp sensor gets hot. Swapping sensors did not help

[Bmw679]

Fan clutch

[Killacortes]

I'm not sure how the fan clutch would cause the car to stall when it's at operating temp? Car does not overheat

[Killacortes]

Anyone have ideas on what else i could test or check?

[ahlem]

Compare the readings from the coolant temp sensors with the Bentley manual.
How many coolant temp sensors do you have, one or two? Do you have the correct ones connected to the right plugs? Did you reverse the plugs? If you jumper in a resistor with the proper resistance to the one that goes to the ECU per the Bentley manual, does the car run right? Is your motor put together from an assortment of early and late model parts?

[Killacortes]

Coolant temp sensor has two prongs and the coolant temp gauge has one prong. Both are connected to the right plugs. Car still does not run right even with different temp sensors at different readings when the car is warn.

Car has a eta bottom end and i top end

[Kershaw]

Time to switch to megasquirt. Not even joking.

[Killacortes]

Time to switch to megasquirt. Not even joking.

That's what my buddy suggested. But if i can't figure this out, will it affect going standalone?

[Killacortes]

Any more ideas?