check to make sure you have a slight deflection in the trottle cable of about an 1/8". if it may be hanging up the plate slightly...those do have a stiff spring and do stick a little when new.

check for vacuum leaks like was advised above. i'm assuming they only removed/replaced the throttle body, but if anything else was removed like manifold or iacv check to see if there are any leaks there too or if the iacv is plugged in.

check to see if the tps is calibrated correctly. if it's obd1 then pin d11 inside the ecu and ground somewhere near should yeild some where near .5 volts closed and 4.5 volts wot...do this with the key on and engine not running obviously.

obd2 does sort of correct itself, but probably not this issue...mostly on fuel trims, etc. disconnect the neg terminal for a couple min just to see if you can clear out the memory, but that's probably not it.

good luck.