Heavy pedal, high RPM's and truck slow to move
 

Hi, my issue has become more urgent.
History:
"Got a check engine light 3 weeks ago. Truck would react slowly to accel pedal. Scanner showed P0720 code. Cleared code, truck drove fine for a week, <150 miles. Got light again, truck more symptomatic, got a new sensor, installed it, cleared code. Truck drove fine for two weeks. Now the check engine light on again. Anyone chase the wiring or grounds? "new" sensor could have failed, but would like experience/opinions. 120,000 miles. Stock."
Cleaned up Battery connections and Positive lead to TPIM/underhood power distribution.
Cleared code.
Drove ok for 30 miles.
Heavy rains last night. Start truck , runs ok then while merging onto freeway, truck slows, mash accel, rpms rise and it acts like the torque converter is slipping. Now no check engine light. Any ideas?
Will check trans level Sat.

Have you checked your fuel filter and air filter?

Sounds like your transmission has failed. Even if the original symtoms might have been low trans fluid, you continued to drive the truck. That would have killed your clutch plates.

Thanks for the replies. I grounded the truck Thursday night after merging onto freeway and it scared me with the flaring/slipping. I just did oil, oil filter, fuel and air filters last week. Going to Trans shop Monday morning. In city driving, low accel, truck was ok. So low to mid accel would act ok, it wasn't until heavy pedal did it flare/slip. Tempted to buy a solenoid and pressure sensor, change fluid and filter, and adjust bands myself, but would rather get a professional diagnosis. Had Trans shop do required maint. on this trans during the last 9 years and hope its not toast. They are a great shop.