1994 Honda Civic Hatchback
D15B8 M/T with P2K intake manifold (MAP, TPS, FITV, No IACV or other sensors)

7 days ago everything was mostly normal with just an idle surge that would go away after a minute but after cleaning the throttle body to hopefully fix the idle surge it fixed it after the first start but after that it went back to a bad idle surge so I tried troubleshooting the sensors and cleaning the FITV + screwing back in the circle piece all the way but the idle didn't fix and now there's a new issue when I press the gas pedal the rpm goes right up to 3K or 4K rpm and if I press it like a tap the rpms jump around even louder but same as 1.3K-1.5K and this makes it impossible for me to drive. I tried adjusting the idle screw and throttle wire but it still behaves the same and I've been stuck on this for the past 7 days and can't figure it out. I replaced the throttle body gasket but it still behaves the same and without the throttle cable connected the issues still are present.. This has been driving me crazy so I would really appreciate the help.

 

When I turn on the AC I'm able to stop the bad idle by holding the throttle body closed tight and the engine sounds like how it normally did before this all happened but if I let go of the throttle body it goes back to a bad idle but trying to do this with the AC off doesn't work and the bad idle stays

 

Based on just this right here, it’s clear you have a large leak. Hopefully, you can revert any changes you’ve made back to what they were, and correct the leak.

 

Yeah this was a leak but it was the throttle body gasket (P2P gasket on P2K throttle body) which I corrected then the leak went away then after over a half of a month later of troubleshooting everything and doing maintenance I totally forgot to do (No coolant) I finally connected an IACV and the bad throttle response on low input went away so just because I was missing an IACV this happened but I can only use it without coolant hoses and not mounted on the manifold because I need a manifold with the IACV holes so zip tied to firewall temporarily. This was a very confusing solution as I've been only using a throttle body + manifold with only TPS, MAP, FITV for years and the throttle has been fine.

tl;dr Wrong gasket used for throttle body (Fixed idle), IACV needed to fix throttle response so if your throttle response randomly got bad after cleaning the throttle body and you have the incorrect manifold this is probably why or could be something else (Fixed throttle response)