Engine swap and car idels rough

So I did the swap and the car run smooth at high idel but as soon as it wants to drop to a lower idel it starts to stall and the idel jumps back up and slowly comes down again... I swaped a 2000 L67 in to my 98 gtp I used the 98 throttle body and 98 injectors and the engine ran great before install... My only idea is I think where the egr plugs into the headers looks like there's a big gap... Will that cause the rough idel problems? Thanks

If there's a gap in the tube that goes from the UIM to the EGR then this may cause a severe vacuum leak.

On the L67 it goes from the rear mani to the EGR, then from the EGR to the LIM.

Yes, if there is a big gap, that can cause an issue. If you feel exhaust coming out around it, then you need to seal it up better, or delete it.

Actually same for the L36, EGR to the LIM; not UIM. Sometimes I let my fingers do the talking.
Thanks machine.

I Spent a lot of time checking for leaks and found it was the throttle body was leaking from the gasket.... Runs like a top now

I Spent a lot of time checking for leaks and found it was the throttle body was leaking from the gasket.... Runs like a top now<br>