(SOLVED) New throttle body casued P0300 Random misfire

[Sether]

Hey guys today I put on my ported throttle body (From ZZP) on my bonnie and all of a sudden its just misfiring and idling horribly. Then it almost kills itself just sitting and with then rev high to stop it from dieing. If i give it some throttle it will take an unusual time getting back down to idling RPMs aswell which is a weird behavior. I've taken it off twice and back on and I dont think there is any way that air could be escaping from it. I bought a new MAF to be sure and that was a big waist of money and I tried replacing the other 2 sensors from my original TB and it started up better but then continued to do the same thing. I really dont know how Just replacing the TB could of done this. Also when i took it out on a drive after puting in the new MAF it drives just fine and there are no signs of misfire at all, then if you are at a stop for more then a few seconds it will go right back to its misfire.

I also used exhaust wrap on my cross over on my headers and used the black silicone spray on it, but the mating surface to the TB was covered with a plastic bag and had a rag in it to protect it. Just mentioning this incase for whatever reason its relevant. Any help would be appreciated ASAP as I dont feel comfortable in driving it in its condition.

[harofreak00]

Sounds like a vacuum leak to me. Check all the rubber fittings, they love to crack, especially if you bumped them during the install.

[96 SSEi]

you got scan data?

if the miss is only at idle, I would first check the IAC. and verify that TP is correct value

just for giggles, unplug the maf and see how it runs.

[Sether]

you got scan data?

if the miss is only at idle, I would first check the IAC. and verify that TP is correct value

just for giggles, unplug the maf and see how it runs.

Not sure what to check? Because like I said I did switch out the reused one from ZZP for my own. Is there a certain way to put it in that i dont know?

[96 SSEi]

ok, did you replace the throttle body gasket?, i think its paper and its NOT reusable.

that would cause a miss at near idle

[Sether]

Sounds like a vacuum leak to me. Check all the rubber fittings, they love to crack, especially if you bumped them during the install.

You were absolutely right. Thanks so much for the advice. A vacuum line basically fell apart that I didnt notice because it was under part of the wiring harness. Now she runs great.