What the %#@*&?? runnng problems
 

Here is a really strange one: 88 model. ONLY when the a/c is on and the hood closed the car goes from smooth running/ within spec c.o. to high c.o. and lumpy running. The fans are on and pulling the right direction, the radiator and condenser are clean- no debris. The owner already replaced mass flow sensor, checked grounds, alternator output w and w/o a/c on. We put a shop blanket on top of the a/c snorkel brace to the front latch (simulating hood closed) it does it. With the air intakes open, it keeps running fine. With the snorkels off all the way to the air cleaner, it runs fine. Yes, the front grill is wide open too.
Short of driving around with no hood, does anyone have any ideas?
:confused:

Just a guess...................................

It sounds like a "heat induced problem"

Therefore, it may be the Temp II sensor, or the Thermo Time Switch. On my '83 they look just about the same, they are on the front of the motor where you can find them easily, one on the passenger and one on the driver side.

The Thermo time switch controls the cold start valve. Other than that, I'm at a loss.

It's just a hunch that the closed hood may be creating more heat under the hood that affects the sensor. Good luck.

PSmileWavy