GM-GMC: 92 Chev 1/2 t 4X4 missing in gear, mass air flow, intake leaks

Question
My truck 92 chev 4x4 auto trans  5.7 engine starts fine, but when it warms up if I put it in gear I have to step on the gas to keep it running. If I take my foot off the gas it dies.  I have changed fuel filter, plugs, pvc valve and checked and tightened carb bolts.  When engine is warm the idle fluctuates a little in park, but doesn't die, if I hold gas to 1500 rpm there is no fluctuation in that high of an idle.  I do have an exhaust leak on the passengers side at the connection of the manifold and exhaust pipe, could this be the cause?  I disconnected the TPS and it made no difference.


Answer
the exhaust leak could be the source if it is before the o2 sensor. or it also could be a vacuum  leak in the intake or a cracked or missing vacuum line. a good way to check for intake leaks is to spray carb cleaner or starting fluid in suspect areas if the idle raises then thats the source of the leak. it could also be a bad mass air flow(maf) sensor or manifold aboslute pressure (map) sensor depending on what your car has. i would check for leaks first thow