Idle burps up and down...
 

I just swapped motors in my 87 gxl and I'm guessing my issue has to do with a sensor or part of the air system (BAC or something). Car starts fine, drops to idle and then it starts to burp the idle up about once every second. I don't know if this is common or not but any help would be appreciated.

TPS out of adjustment or bad.

http://howto.globalvicinity.com/gv_w...i=58&co=1&vi=1

same thing happend to me. my tps was bad test that 1st

Alrighty, there's a few things I've left out and I've done work to it since I posted last. Symptoms are it idles between 1400 and 1600 rpm and when I get to 4000 and give it throttle it lugs bad. When the motor was in the donor car it had the same issue. I've swapped primary fuel rail, UIM and TB from the engine that was originally in this car. I guess my next step is to get rid of all emissions and run new lines throughout. Curious as to any other feedback. Thanks

stuck tps? bad vac leak?

Definitely check for vacuum leaks. as much as a pain in the ass it can be i would start there. I had this exact problem just a couple months ago and it ended up being that the solenoid thats part of the accelerated warm-up system was stuck open. But theres alot of good advice and things to check in that thread

Read through here. And if you search you will see its a very common problem.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/yes-another-f%5E%24-ing-idle-problem-841652/

Cold idle is supposed to be at about 1500 RPM. If it never goes lower than that, your throttle stop could be adjusted wrong, or the thermowax may no longer be functioning properly. This would prevent the cam from rotating, which allows the throttle plates to settle against the stop.

The 4000 RPM issue sounds like the secondary injectors not firing. You can probe their wiring with a multimeter. It should show 12V at idle, if they are powered.