1994 Ford Tempo

I have a 94 Tempo (I bought new) with 165,000 miles. The car has recently developed a miss while accelerating. A slight miss is noticeable at idle. Also if you keep the rpm's up it doesn't seem as bad. I have replaced plugs, wires, cap, rotor and added injector cleaner. Any ideas.
This car has never given any trouble.

have you checked the vacuum hoses or sensors? Did you check to see if your MAF sensor was coked up with oil or something? What about the throttle position cable, or even EGR? Is your distributor adjusted properly? Above all, do you have a manual?