I have the same problem as everyone else, My 1989 109E 2.6 engin# 103.942, chassis# 201.029 with CIS stall like the key was shut off when it is over 85 deg. C. but starts rite back up. Also it idles low, 500rpms as soon as it reaches 85deg all the time. these two problems may or may not be related, I don't know. I see you all talking about this but no complete conclusions. I believe it's a heat soke issue, but what part? It has to be electrical, I've checked fuel flow and pressure.
I changed the 4wire temp sensor and the OVP relay.
First question: what tells the engine computer how fast the engine is spinning? The crank sensor?, the mas airflow?, the manifold absoulute pressure sensor?, just the RPM sensor or all in conjunction. What would heat up the most?
Something is telling the computer the engine is spinning faster than it really is and is closing the idle air control motor, I cleaned the IAC with Brake Cleaner, wasn't really dirty. I tried to raise the base idle with the throttle plate adjustment screw under the MAS and the computer put it back to 500rpm, only the TPS advanced base timming, so I put base idle back. When engine cools back to 85 deg. C the stalling stops and idle goes back to 650rpm. I pulled out the timing resistor and this did give me 25 more rpm and more hp.
This only happens when its hot, so my next step is to heat up each part with a heat gun until it stalls.
It's all guess work for me, anyone got any ideas?