2001 Toyota Camry gas pedal sticking at top (not at floor)

Problem: Sticking gas pedal
I replaced a malfunctioning throttle body assembly(stalling while driving) on a 2001 Camry 4 cyl, with a used one. The used one works fine, except now the gas pedal intermittently sticks at the top just when you push it (not down at the floor). You have to give it a little kick to unstick it and go. It mostly happens taking off from stop lights, and only after the car is warmed up (10 minutes of driving). I got a refund on this used throttle body, which is still in the car, and I've found another used one. Should I replace it again, or could it be something else?
Lubing at the floor linkage and under the hood where the throttle cable connects didn't help. Cleaning inside the throttle body fixed the problem for 2 months, then it came back.

Thanks