Hello,
I had this happen to me on a 90 GT I had a couple years ago.
I replaced the motor with the GT-40 345 Hp crate motor. After that I had the pop in the intake when cold. When looking around I discovered a vacuum leak between the upper and lower intakes, beacuse the bolts weren't tightened all the way. The sound went pretty much away. It totally went away after I put a cobra intake on. So I do believe it was the vacuum leak.
I have also read that intake pop can be a emissions device problem. Like a stuck open EGR valve.
__________________
meknized
 Blue/silver 89 GT, Coast 331, ported GT-40x heads, X cam, cobra intake, 70mm TB, 75mm bullet, mac intake, 24lb inj, 255 lph fuel pump, accufab regulator, pulleys, MSD coil, 6AL, 300+ wires, Tremec 5 spd. pro 5.0 shifter, FMS drive shaft, headers, X-pipe, flowmasters, auburn pro series posi. moser 31s axles,3:73s, etc. Best ET 12.02@112.5
a pic  A vid of a run: http://www.youtube.com/watch?v=l9JMcErxML8
|