92 5.8 idle problem

my 92 econoline 350 with the 5.8 EFI engine starts up and run smooth when cold but when the engine gets up to temp the idle revs up and down like it wants to stall but doesn`t ..if you step on the gas it revs fine when you let go theres a couple of seconds of hesitation then it idles up and down again :screwy: :smokin: any ideas where to start?

Have you checked to see if it's throwing any codes? Could be related to the EGR valve.