Loss of engine power
 

I have a 1988 Rx-7 (coupe, 5-speed, non-turbo). I'm having a rather strange problem and I wonder if someone can help out.

If I start my car and the engine/coolant is cold I have no problem. Also, this problem does not usually happen if it's cold outside (outside temp. under 50 degrees F).

However, if it is a warm/hot day outside and I've driven the car for a bit (say 1/2 hour) and I turn off the engine for a short period of time, when I go to start the car up again I often have this problem.

The problem:
I start the car fine and I'm able to rev the engine (while in neutral) up to 4000-5000 rpm just fine. However, shortly (10-30 seconds) after I start to drive the car, I lose engine power. When this happens, when I give it gas, the rpms will not go above 2000. Even if I'm in neutral, the rpms will not go above 2000. Once this problem happens, there are only two ways I know to get past the problem; first is to let the car sit (cool down) for a while (1-2 hours); the second is to accelerate very quickly in first or second gear (getting the rpms up around 4500) for about a quarter of a mile. Once I get past the problem and I am driving the car, everything is fine as long as I don't turn the engine off. This problem almost never happens when I start the car when the engine is cold (even if it's a hot day). Also, once the car is "going OK" I don't have the problem while driving. When I'm having this problem, the car is not overheating - the temp. gauge looks fine.

Since this only happens on warm days after the engine has been running, I assume the problem is temperature (coolant or engine temp. at startup) related. I'm guessing it's related to the F.I./Throttle. I'm wondering if the problem is the water thermo valve or maybe the thermo wax device. I've replaced the thermostat so I know that's not the problem. Has anyone seen this problem before?

Thanks,

John