What are the signs of a bad intake manifold gasket? When I start my car it jumps straight to 4k rpm and backfires. It just has the startup tune so I know it's gonna run like crap but I noticed my boost gauge is not reading any boost/vac either. Ive checked the tps and iac valve for the high idle and both are brand new and seem to be functioning just fine. I've also checked all of the vacuum lines by blowing. Compressed air in to the system and everything is tight and leak free. What do you guys think? Did I mess the intake mani gasket up when I installed the blower? Thanks!