i just recently bought my o3 gp se off my brother with a knocking 3100 motor and decided to put a 3400 in it instead of the 3100 its the same motor just a little bigger bore .every thing went smooth swapping them it runs beautiful when running the only thing is it has some starting issues ,on a cold start it just cranks a little to long then starts the idle jumps around a little bit then drops down to a normal idle or stalls some times but starts right back up. any one have any ideas?

No clue. Welcome to the board. A 3.4 swap hmmm different. Most opt for the 3.8.

3.4 swap is different. Different BAD. While the 3100 is known to spit head gaskets, the 3400 is even worse. It's known to warp heads, intakes, spit gaskets, and also to be a fragile motor. I would go for the almost bullet-proof 3800.

have you started to address fueling issues? I would look at fuel filter and pump first, clean injectors, replace injectors.

Not getting any fire would cause a similar issue, but you would get a misfire code or six. Cure for that is plugs, wires, ICM and coils.

Start cheap and go big from there.

Welcome to the board, hope you enjoy your stay.

Try unplugging your MAF and see if that works. Also look at the TPS and IAC and clean them if you have to.

it is the ohv 3400 not the dohc 3.4 .i used new plugs, wires ,my original coil packs and module ,cleaned the iac .Ive had a couple 3800 powered cars they are great but wasn't trying to change to much this is just my daily driver .i have other toys haven't checked any fuel issues yet the car started and ran fine be fore except for the knocking .but i am gonna still check though.

how do you add pictures on here?

read through the FAQs. Step-by-step instructions there.

Did you try unplugging the MAF? I would start there as that is what it sounds like to me.

Fuel filter?

I'm going with MAF.

Its in the everything else FAQ

Almost sounds like a sparkplug/wire issue... Are you throwing any codes?

no codes .new plugs and wires runs fine after it starts

Yeah, internet decided to hang on me. I thought the first post didnt take, so I hit Submit again. The duplicate will be removed. Thanks, Mike.