Need help...plz
 

89' GXL 85,400 miles

Sup guys....I'm new here but plan to stick around for a while..I need some help on my rx7 which I recently bought. I replaced the spark plugs and wires at Pep Boys as soon as I bought it. But even though I had done that....the same problem still occurs. The RPM does not stay idle(still)....it continues to move up and down(between 1500 to 2000) when my foot is not on the gas. And at times the engine knocks and the car shakes alot when the car is idle. I took my car to the mechanic thinking it might be the idle timing or O2 sensor....but nada....The problem still occurs and I still don't have that great of acceleration...And ideas guys?

get a haynes manual, check your tps (throttle position sensor). Also may want to change the fuel filter if you don't know when it was done last.

Also check for vacuum leaks.