89 Suburban problem

My 89 Suburban 2500 with the 454 will start and run pretty good when the engine is cold. But after the engine is hot or has been running for awhile the Engine will idle rough and sometimes stall. Anyone have any good ideas of what seems to be the problem.

First thing, check for any error codes. Then I would do a tuneup (rotor, cap, plugs, wires). Could be anything from a bad dist cap to a plugged catalytic converter.

Quickest diagnostic is have a shop run a scan on the engine as it warms up. These old GM's don't give near the info that the OBD 2's give you, but you should at least get pointed in the right direction. From a cold start, your ECM controls the engine in open loop until several conditions have been met including engine coolant and exhaust. Lat us know what you find and we'll go from there.
Don't start throwing parts at it yet. It could be as simple as a loose hose on your MAP or EGR.