Hello All,
I have an '06 Silverado 5.3L, flex fuel with 18,496 miles. I have installed a Volant CAI, JBA cables, Magnaflow dual exhaust and Hypertech III programmer (only adjusted the increased tire size and shift hardness). Here's my problem..... just this past Tues morning (May 6th), I heard a "hissing" noise coming underneath the dash, driver's side (sounded like air escaping out of a tire). It stopped as soon as I stepped on the brake. Yesterday morning, it happened again and after lunch (going back to work), it also idled roughly. Again, as soon as I stepped on the brake, both stopped (hissing stopped and started to run smoothly). I have taken my truck to 2 different Chevy locations and both were unable to find the problem. (The 2nd service center, I had left my truck over night so the can start it up cold.) The 2nd service tech said that it may be my programmer. This is odd since I've been using it for over 2 years without any problems. Does anyone have any clues that they can provide me? Thanks!

Mike