A very common problem with these is the throttle body gasket. I can't count how many I've replaced. What happens is the engine sucks the gasket out from underneath the throttle body and it creates a large, unchecked vacuum leak. One thing you'll notice is a loud sucking sound and a higher than normal idle speed. It can also be harder to start. The MAP sensor will sense a different manifold pressure than what the other sensors tell it it should be, and the fuel curve can change as a result. It won't always turn on the check engine light either. Since the engine will be running leaner than it's supposed too, it can cause a lean misfire, power problems, and overheating concerns. Quick check is to check for hissing noises other than the normal noise from the throttle body. Then take some carb cleaner and spray it all around the base of the throttle body and plate under the throttle body if it's equipped with one. If the idle quality and speed changes, it's a sure bet that it's bad. The gasket is pretty cheap too, and they are easy and quick to change. Might just check it out anyway, since the carb cleaner will cost about the same as the gasket unless you already have some on hand. Hope this helps.
Mark