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.

 

Check the spark timing, if it's way off the timing belt could have skipped. Consider a new timing belt anyway if you don't know whether it was ever replaced.

 

I do not know if it is new, but it sure looks like its been replaced before. I get no check engine light either.

 

How much is the timing belt?

 

Hmm..about $22 at Autozone....just shop around.
You might want to tighten your acceleration cable as well if there's any slack.