Re: what the heck is going on here?! (gti1497)
Any unusual exhaust coming from your car? ie black or gray smoke?
Your engine needs three things - air, fuel, and spark - to run right. Start checking the basic maintenance parts in each system. Something tells me your problem is going to be something simple and cheap, but possibly hard to find.
As G60247 said, vacuum lines are very important to the engine management system in these cars. Especially that one running from the throttle body to the ECU. The ECU has a MAF (Manifold Air Pressure) sensor in it, and that sensor is the main way the computer knows how much air is entering the engine, and thus how much fuel needs to be added. So, if that vacuum line is defective, or not the exact right length, then you are likely to have problems - running way lean or rich, which is what it sounds like your car is doing.
So check and measure that vacuum hose. The o2 sensor is also important and cau cause problems like this. After those two items check out fine, go over your ignition system. Are the plugs in good shape? the wires? cap and rotor? Check the ignition timing, too. After that, I'd say look at the fuel system - are the injectors really dirty or clogged? Is the fuel filter a million years old and so clugged up that the engine isn't getting proper fuel flow?
For the vast majority of problems, a forced induction car isn't much different than an n/a car, so you probably know what to do already, even if you don't think you do. After all, the only real difference is that one blows and the other sucks - they still both have the same basic needs and the same basic support systems.