Troubleshooting Help

[Jseverin]

The stumble when you let off is very common when using upgraded maf like lt1, ls1 it 85mm. They read air moving in and out so when you let off the gas, the air built up in the intercooler comes back through the maf triggering fuel and causing the stumble.

The best way I've found to check for vacuum leaks is using a shop vac. Put the hose on the exhaust (blow) side of the vacuum and the other end to the intake pipe or throttle body. Switch on the vacuum then use a spray bottle with some soapy water and spray suspected areas. I see a lot of leaks around the EGR block off and vacuum block.

Maybe I just missed the leak. it's gotta be vacuum b/c when I parked it at yesterday it was idling between 900-1000 rpms. I usually see 750-800. That coupled with high blm's (that return to the normal range while at highway speed)seems like a classic vacuum problem from what I've read on these forums. I am also starting to suspect a new chip might help. I am reluctant though because other than idle and low speed the car runs great at highway speed and makes 22lbs of boost without a second thought. I don't want to mess with it b/c I admittedly have no idea how to tune it and the guy that set it up is back in Texas.