When my rpm's are rising it doesnt backfire but when i downshift and they go down it pops, and sounds really rough, i dont have the MAF sensor hooked up because it idles at 3000 when its hooked up, could that be the reason? I also spoted an 02 sensor was half melted and only half plugged in. Brand new opti-spark brand new wires, brand new plugs. Any advice helps, thanks!

 

i know my 02 pops a bit when lifting off the throttle. as far as i know, thats normal. yours doesnt sound like it though. and i think you may need a new maf if it causes that big an idle problem

 

Sounds like someone may have deleted the cat.

Why do you drive around with a faulty MAF and a melted O2 sensor? Both those can cause problems with the way the car runs. Fix it. It deserves better.

 

well how can find out if the MAF is bad or not? sometimes it runs good with it plugged in, other times it idles at 3000 until i unplug it then it runs good but the service engine soon light comes on. Also the reason i have not fixed the O2 sensor is because the part that got melted is part of the wireing harness and i can't find another one...

 

You can buy "pigtails" - short lengths of wire with the correct harness connector. Shoebox has part #'s:

http://shbox.com/1/Parts.htm

Look at the right hand column on that page.

With the MAF sensor plugged in, do you get an SES light? If so, read the code. If not, its probably working OK. A faulty MAF sensor will not affect the idle. I think its just a concidence. For the idle to increase, there has to be more air getting into the engine. Could be stuck throttle blades, could be an intermittent vacuum leak, could be a problem with the idle air motor. You've got to systematically eliminate the possible causes. One way to prove the MAF sensor is not the cause would be to swap your MAF sensor with someone else's and see if your engine runs better, or theirs runs worse.