wondering if anyone can give advice. Bought 2005 suburban with 38K miles on it about 6 months ago. After 2 months check engine light and reduced engine power went on. Took it to the local dealer in Norfolk Va. Codes showed throttle body issue and part replaced. 2 weeks later same issue, took back in and had the "wiring" replaced per senior GM tech advisor. Ran fine until over the weekend when I was towing my boat across the cheasepeake bay bridge with the ac on and it powered down to max of 10mph in the first tunnel....lots of fun...Turned engine off and restarted it and it ran ok for about 30minutes with ac on and same thing. May be coincidental but once i turned the ac was turned off it did not happen again, but i was turned around by that point and was close to home. CK engine light off and reduced engine power off this am. Fuel to the flame......Turns out when the truck was under warranty from prior owner and the throttle had already been replaced about 10K before i bought it....although i did not see record of this on car fax! Any rec's on what the real problem may be?