The TCC solenoid is located inside the transmission and replacement is not a diy job. Costs about $500 to replace. The description you gave when you take your foot off the gas pedal indicates that the TCC is disengaging causing the issue to go away. As for the stalling the problem there is probably caused by the Crank position sensor going bad. I would replace the CPS before doing anything, if it is weak it could cause this issue and can account for misfires. The stalling issue is the critical one at this point.