1992 Tempo GL 3.0L missfiring
 

I have a 1992 Tempo 3 liter that seems to be misfiring. when it's idleingit bogs down every few seconds and the rpms drop and come back up quickly. it does this about once a second when in idle. when you try to accelerate from a stop it hasno power and it jolts the whole car, it seems to smooth out slightly when you get up to cruising speed but it doesn't go completely away.i have already replaced the rotor, rotor cap, wires, plugs, air filter, fuel filter, and haveran two tanks with injector cleaner. but the problem is still there. i think that it might be either a bad injector(s) or bad oxogen sensor(s). but i need to narrow it down because i can't afford to replace both. Oxogen sensors run $60 each and it needs two of them. injectors run around $300 fro a set of six. i alsoran the car on a code reader but it didn't come up with anything. has anybody delt with this problem or have any suggestions? any help is appreciated. thanks.