I have a 1990 Turbo II. I notice that the engine doesn't seem to produce quite as much power after the car has been started while the engine is still warm.

For example: I start the car in the morning when the engine is completely cooled off. I allow it to warm up a few minutes before driving, as always. I start to drive and notice that the engine runs very strong, and can see the boost gauge reading anywhere from 4.5-5 psi. Now, suppose I let the engine cool down a few minutes, and shut it off. I come back about 30 mins later and start it back up. The engine is still warm. Now when I drive it, I can notice a slight decrease in power and notice that the boost gauge will read about 1.5 psi at best.

No matter how long I run it initially before turning it off, it will continue to run strong. The problem is when I return to the vehicle and restart it after it's been off and the engine still warm.

By the way, everything is stock.

Any suggestions to what this might be?

 

My guess is heat soak of the intercooler. If you keep the car moving, it will help ward off heatsoak, but once you stop it all the heat seeps into the intercoolet, reducing its effectiveness.