Engine stalls after trans replacement

Hey All,
I have a 1987 GMC Jimmy, 5.7, 700r4. I recently had the trans go out. Money was (is) tight so rather than rebuild it I took a friend up on an offer for a used one for basically free. I installed the trans and it seems to work alright (shifts ok etc...) but I have a problem with the truck wanting to stall after it has been running for a while. At a light it will idle very slow and often want to die. It does this only after running for a while. At first start up everything is good. Could I have a torque converter sticking in the lockup position? I did not replace the converter when I did the trans (that will teach me to be cheap and not want to spend the $$$).

Any help will be greatly appreciated!

Brian

possible, but doubtful, cuz if it was sticking it would kill it just like if u didnt push the clutch in on a manual transmission, i would kill it dead not slow it down

possible, but doubtful, cuz if it was sticking it would kill it just like if u didnt push the clutch in on a manual transmission, i would kill it dead not slow it down

Thanks for the reply. Do you have any other ideas what it might be? I dont have any wires or vaccuum lines pinched or disconnected. It ran like a scalded cat before the trans swap. Im stumped.