I changed the fuel filter recently the plugs and wires were changed about 1500mi ago oil changed about the same time, the car idles normal and doesn't misfire or hesitate. The car is very sluggish to take off from a dead stop, the mid range power is near normal the exhaust tone is different too it sounds slightly muffled. I took off the air intake cleaned it out and cleaned the filter and it ran perfect for about a half mile soon as i turned around to head home it started running funny again. Thank you ahead of time for reading and for answers.

 

did the issue start after the parts where installed or was it goin on before? what kind of air filter do you have. paper or k&n style?

 

Check to see if your cat converter is getting red hot after a run. It may be restricted (broken up or melted down inside), and in need of being removed/replaced.

 

The filter is a K&n filter, I did the tune up and drove from Kansas to Michigan from Michigan to Virginia with no problem at all with pretty good MPG too. I was thinking it was the Cat but I figured I'd try the cheap fixes first it has been running pretty hot lately but I will drive it around and check it and see.

 

Sorry forgot to answer your first question. No i was not having the issue before I don't know a whole lot about cars but I was thinking it might have been caused by the tune up but then again I drove about 800 miles (one trip) on it like a week after the tune up and then another 800 a little over two weeks after that with no issues at all.

 

running a bit hot?
head gasket?

 

one way to check cat is pull your 02 sensors and run to see if it makes a difference . the o2s gone lets pressure out, the motor will run in open loop till 02s are installed and functioning.