Just randomly i was driving my 9 and around 2500-2800 RPMS it starting bogging down. Then coming to a stop it would drop to 300-400 RPMS, bounce back up drop back down. Did a cold start the next morning. Did they normal 2K rev then began to drop and rise drop and rise. Checked intercooler piping. Wondering if anyone else has or has had these issues?

 

Did you make sure it has no boost leak?

 

Possibly a vacuum leak somewhere or throttle position sensor.

 

Most likely a boost leak. Could also be the IACV going bad(not too likely). I had this problem and it was actually my BOV that had the boost leak. I took it apart, cleaned it, and oiled it with mobile 1 synthetic and my car stopped doing it.