Put in a new fully rebuilt z6 in to replace the old one a few weeks ago and put only 650 miles maybe and ihave an issue that is inconsistent where I can't rev over 2k or it sounds like I have a rev limit and if I downshift to anything above 2k and gas it it bogs already replaced iac valve fast idle valve tps and still idles rough aand does this... anybody had this issue or any ideas to what is the problem my next guess is fuel pump or filter

 

Distributor....

 

But another weird thing is that when I start it it idles at around 2k then u hear a pop (small sound like as if something was plugged) and drops idle to like 6oo rpm and if u hit the gas and let off it will idle at almost wanting to die