Ok what are some things that can make my car slow. Everyone I have talked to about it says the car runs to good, to be anything big. I have a check engine light that is from my smog system not being there. but ill get you guys the exact codes tommorow. what are some things that you think should be fixed or replaced.... Acouple days ago i put in a new maf, givin it was a remanufactered one from autozone(were i work). but it made my car die when i put it in gear and run really rich, as to were there was black smoke comming out the exhaust. i put the old one back on. i have done a basic tune up on it but im lost as to were to start now. the car is a complete dog. 15.8 is the best e/t i have so far with a best 60ft of 2.29(need new tires bad). with mods in sig. Please help. what are some sensor and stuff that goes unnoticed? im starting to think it might be the fuel pump.