Stalls and Bucks

[dckingan]

Problem - Engines starts and idles nicely 650-700 rpm. After warming up it will sometimes stall when coming down to idle at a light or sign. It will restart but goes crazy running 2500-3000 rpm until it recovers and comes back down to a normal idle. Also when decellerating with foot off the gas pedal and reaccellerating it hesitates and bucks like the engine had stalled and restarted. I have checked and repaired all vaccum leaks, rebuilt all the injectors without success. It does appear the idle screw has been tampered with, if there was a plug on the adjustment screw it is gone now. Any suggestions would be greatly appreaciated.

Thanks in advance,
Dennis