On my 1990 240 Volvo DL non turbo, my car does a rough start only on a hot engine. On cold start there is no problem. The problem is on the rough start is it acts like it wants to die out, and the engine light comes on for a sec...untill I rev the gas. once I rev the gas for a couple of secs the engine runs stable and check eng light goes off. Again, it is only when starting on a hot engine, not a cold start. What could be causeing this?

Here's what I've done in the last 3 months to improve my car and try and fix this problem:
New oxygen sensor
New Flame trap filter
New oil change and filter.
New fuel filter(outside fuel filter)
New spark plugs, wires, and rotor cap.
New air filter.

 

It could be possible that your cold start injector is coming on when the engine is hot causing it to run mega rich until you hit the gas. Does it smell like gas when you first start the car?

 

Clean the Idle Control Valve, the big one under the intake manifold: take it out and run some ceaner through it. Also, it could be the Fuel Pressure Regulator-pull the vacuum line and if you smell gas, replace it.

 

Check the temperature sensor leads

 

bookmarked and b back l8er, bro, :-)

 

What does the code read? Sounds like the Idle air control valve.