Just finished replacing 100% clogged heater core in '02 Blazer LS 4WD. Took 10 hours but now we have heat! Only problem is, truck stalls every time we put it in gear. Idles great, everything seems fine but reverse, drive--forgot to check neutral---but it immediately stalls. If keep foot on accelerator, it'll go but soon as you take your foot off the gas it dies.

Any ideas or suggestions? The more I think about it the more puzzled I become. First I thought maybe a wire in the steering column got nicked but that doesn't make sense. The only vacuum lines we messed with were for the AC in the dash. Had to drill a hole in the heater blower resistor housing to access the bolt that holds the core assembly to the fire wall but that wouldn't have anything to do with the transmission.

HELP!!!!

 

Neighbor across the street suggested I turn ignition to on and let sit for ~10 minutes to reset computer. Must've worked..

Truck runs like a champ. Heater runs like a champ. Life's pretty darn good here in Sloan, NY, at this particular moment. 29° wind chill here but toasty in the truck. Thank you, God!