Rep Power: 0

I bought this car used, it has about 148,000 miles. It ran pretty good as far as I knew. I gave it a tune up right away, changed the oil (mobile 1 synthetic), spark plugs and cables, and tranny fluid. I noticed by the oil pan gasket and tranny a small amout of oil leaking, so I went to the mechanic and suggested it was probably the valve cover or the distributor o-ring and also said it looks like I have a blown gasket(how do i know if its blown?it worked fine). I changed both and it still leaked. Then I noticed the fan was not turning on and it was the sensor and themostat, so I changed both. Then everything seemed to be working, but after doing the themostat I noticed a difference in performance, it felt sluggish, I push the gas pedal all the way down in the freeway just to keep up with other cars going about 70mph. I also notice the previous owner welded the catalytic converter.

Any suggestions on what should I do?

Thanks in advance.

 
Rep Power: 217

If you have a suspicion a gasket is leaking, in your case, either the oil pan or valve cover, start by cleaning the areas up. Get some degreaser, a hose, a brush, and a few rags. Clean up the bay and clean your oil pan. If there's a ton of gunk, you aren't going to be able to see anything. Try that first and get back to us. Did you clean out the throttle body along with the tune up? I don't think it would make much of a difference in performance, though. Is the car throwing a CEL/MIL by any chance?