Stalling in gear/low rpms

[Blackmumba]

My 2003 yukon not 4x4 just regular is starting just fine but if I put it in drive or reverse it shakes goes to 400 rms then just stalls out and I can start it back up but it happens every time I had the alternator checked cause my lights also dim when rolling the windows up or down headlights and all. They said the alternator was good. I had 2 15s in it for a while (could be a cause) I can't see the ground wire but I'm convinced it's something electronic but idk.
Bought a new battery, wasn't it. I need help before I spend more money on stuff that's not gonna fix it.. Please help.

 

[ccapehartusarmyINF.(ret)]

possible the break pedal switch could be bad the break pedal switch is what tells the torque converter clutch to unlock
try starting it up and shift into 1st or reverse and before engine dies shift it into neutral and see if it continues to stall ? or any other gear

 

[rockenthebowtie]

Check your connections to the under hood fuse block from the battery also check the ground cable that bolt to the engine block under the #3 cylinder... when the tcc solenoid stays engaged it will cause more of a sudden direct stall and that will happen more when coming to a stop after tcc is engaged.. you also might want to check for upper intake manifold gasket vacuum leak if you start the vehicle just let it idle in park and get a can of carb/fuel injection cleaner and spray at the base of the upper intake manifold gaskets and see if theres an idle increase if so the intake gaskets need to be replaced

 

[ccapehartusarmyINF.(ret)]

ahh i guess i got it backwards that makes more sense the break pedal switch unlocks the TCC when your driving and hit the breaks
automatic transmissions was kindof my achillies heel when i went to school, our final lab test was rebuilding a chrysler 41TE transaxle lets just say i was nearly the last to guy to finish

 

[Blackmumba]

My alternator tested good 2/3 times today. And thank you I'll tell my step dad cause idk shit about engines. Lmao thanks tho!

 

[rockenthebowtie]

All good C vehicles can be quite challenging and confusing at times for all of us even more so when trying to help someone by just going off the symptoms there describing.... @D... question... the vehicle is driveable correct just low idle/stalls in gear but accelerates and drives ok.. and is the check engine light illuminated ?