Have a 93 Bronco, 5.0. replaced battery, IAV and had a complete tune-up. Now starts great, runs fine until it gets warm, than in about 5 - 10 minutes the idle starts to fluctuate. A little at first but eventually between 1000 to 300 rpm and will stall if you don’t give it some gas. Turn it off, restart, starts fine and runs OK again for a while.
Was the throttle body cleaned?
Check the vacuum line for the fuel pressure regulator for liquid fuel. If you find any, replace the regulator.
Temporarily pull the vacuum line from you EGR valve, plug the line and see if that does anything. Try again at the solenoid.