My 2000 SE is having multiple problems! It's driving me insane. It begun when I started adding after market parts. I added different spark plugs, exhaust, and reusable air filter. It ran great for 2 weeks. Now, If I try to punch it, it will rev REAL high and not go to much faster. Sometimes it sputters at high RPMs. Somedays my exhaust sounds awsome and some days its just ok. There is now a rotten egg smell coming from somewhere. I thought it was the fuel injector. I was wrong. I dont know much about cars. It kills me to have my MAX run this bad. I have added horsepower I can't use. I need desperate help!!! Everyone Ive asked or taken it to, wants to dip in my wallet. Is my problem the fuel filter and/or pump, air flow problem, or possible slipping tran?