S14 weird idle and engine shaking?

[Fbomb19]

Long story short i bought this 1996 zenki about a 1 month or 2 ago. It ran great. Then me and a friend went to a store in it, and when it started the idle wasnt steady. It jumped up and down bewtween 750-1,200 rpms, and then it went back to normal. You guys might say this is normal but i know my car (usally starts up at 1,2000 rpms and then idles at 750). But anyways, Ever since that day the idle tends to Move around and then back to normal and then jump around more. But lately its been doing it alot more often. And when it jumps around the motor shakes (and almost sounds like a misfire but i dont think it does). And i seen it shake and i can also feel it. I looked at the distributer cap and rotor and they wer pretty ugly so i changed those out for new ones. I also changed the fuel filter to z32 fuel filter. And i really dont see why its shaking and causing unsteady idles. If any one of you guys have any ideas ? Please help. Id like to keep my car up to date b4 it leaves me on the road.

Btw some guy i met told me it was a module inside the distributer but idk for sure.
and only mods on the s14 are headers (wich leak a it) and cold air intake.
I know some what about mechanics but i just know broad things. Im really not sure whats going on under the hood tho lmao. So pls any ideas? let me know thanks

[coolbone28]

Does this happen all the time when it is idling? Or only on cold starts? When i first bought my '95 it would surge like yours for the first 30 sec to a couple min going from about 500rpm-1500rpm, but only on a cold start. sometimes i would have to push the throttle a bit or it would die. My problem turned out to be a dirty IACV (idle air control valve). The easiest way to clean it is to remove the vacuum line for the iacv from the intake and spray carb cleaner in there...alot of it haha. There is a kind of technique though.

Remove hose and plug it with your finger otherwise it could stall the motor. Then with your other hand rev the engine a bit...not too much. Then start spraying carb cleaner in that hose while keeping it from dying with your throttle hand. you can do it in spurts to help your idle stabalize. I think i used about half of a can on mine. Haven't had a problem since and its been about 6 years.

[Fbomb19]

when it first started it was on cold starts but now it seems to just do it. Its does it alot when it idles. and itl go back to normal and stopshaking and then start shaking again. I gotten some people to look at it briefly but they dont even know. They had no idea what to tell me. Lol. idk what it is. and it still runs fine. When im driving theirs really nothing wrong, sometimes i feel it shake when i stay in a rpm for a while but it drives good. but when i get bac to idle it shakes and isnt steady =/ . im clueless.

[cmekis]

Did you ever find out what it was?