First off, I have a 1988 rx7 gxl with the stock 13B N/A motor. I got the car as a non running. I did a little work, I replaced the fuel pump and the fuel lines were brittle and leaking so I replaced them. The car wouldn't crank with the ignition barrel so I just hooked up a switch for the time being. After all that, I got the car started! I drove it a little bit and it runs rough. When I first start the car it revs to like 2k for 10-15seconds and then goes down to 1100 and it idles at that. I adjusted the idle screw and the throttle cable but no help there.When driving, at first it wasn't going past 3500 so I figured it was the secondary injectors were dirty or clogged. I went out and bought a bottle of fuel injector cleaner and drove for a little while. After a few days of driving it revved past 3500 so I figured the injectors were clean. I finally decide to drive it on the highway and I went to 5k and it started breaking up, when accelerating it would just stay at 5k and no further, it would just rev up and down at 5k. Last thing is the acceleration is really bad, I can have the throttle all the way down and it won't accelerate quick at all! It will take forever to even get to 5k. The throttle cable is nice an tight! Any help would be great.

 

This is normal behavior, the idling at 1100 is not though. Should be set to 750rpm with the initial set connector jumped to ground.

A bottle of fuel injector cleaner will not do much. If the injectors are truly dirty the only thing you can do is remove them and have them sent out for servicing.

Have you made sure your TPS and Air Flow Meter are working properly? These are some of the symptoms of a faulty sensor or possibly bad compression. The fact that you can't bring the idle down 1100 could also indicate a small vacuum leak.

Bad compression? Blown rotor? Bad AFM? Check compression make sure you didn't buy a blown engine. Then proceed to check the AFM, TPS, water temp sensors. Get the FSM and start going through everything if compression checks out ok.

 

how long was it not running for?

Id say check the spark plugs.

 

I replaced the spark plugs. I will check all the vacum lines and connectors work. Thank you jjcobm it was down for like 6 months.

 

I think I'm having the same problem as asiandude. Mine progressed from not revving over 3k, to 4k, and now 5.5k, so maybe it'll just fix itself eventually

I ripped out my AFM today and there was nothing obviously wrong with it. The FSM tells you to check some resistances between some of the pins, but didn't say which ones to check I noticed that the spring holding the flapper closed seems pretty stiff, is it supposed to be kinda stiff? It doesn't seem like vacuum from the engine could open it...

 

Compression Test

Get the Injectors serviced, or replace them. All of the broken down fuel components you replaced more than likely got some "gunk" to the injectors.

If you were closer I have a set I'd let you throw in there to check.

Suck some water into a vacuum line into the manifold while it's running and up to temp. Have someone keep it running by trying to keep the idle around 2k. - Breaks up Carbon build up.
SeaFoam works too but some will suggest against it.