surging under boost

ok, I have a RB20DET in my Z. I just changed my manifold and dump pipe. Before I did this, when I would up the boost to 12-15psi it would surge under boost and make a studdering noise and hardly move. Sometimes it wouldn't happen, or just for a bit of a second.

Now after the manifold change, it does it even on stock boost (10psi). I haven't checked the MAF yet, maybe it is that? It likes to backfire alot, although after the manifold change it hasn't very much.

I do not have an A/F guage. Nor do I have a FPR.

Got any ideas guys? :confused:

edit- I fiddled with my gain, and nothing changed.
I am running 91 in it (highest besides 100+ in CA).
Also, when I take it out of gear, it dips below 800rpm sometimes dying.

take out and clean the AAC valve, that should fix the dropping revs, not sure on the other issue though

well, I talked to Tat, and we decided that I have a missfire, and I realised my plugs wernt changed after the swap.

As he described it "its like hitting a mini rev limitor" also I noticed it missfiring at idle

anyway, where is the aac on the Rb motors?

ok, I just checked my plugs, they were a lil dirty *from running rich and not being changed for....who the hell knows how long*

and they were gaped at about .043

I cleaned and regaped to .030 and it is running ALOT better.

Any other ideas to help make it run better? Like maby a different ignitor chip? Any cheep upgrades

Also I have some oil in the piping, thinking maby the turbo is slowly giving out. Do I have a T25 or a T28 on my RB20DET?

Any help is much needed!