Idle miss in drive

Nissan Xterra, 2000, Auto, V6 4x4 with 128K. Had a small head gasket leak which was repaired 8K ago. Both gaskets replaced, heads deck lined, raidator core changed out and complete tune up. Truck runs great around town and on the hwy. Stopped at a light, in drive, the engine will intermittently hiccup (miss) where the idle drops off maybe about 150 then back up to normal. If the AC is on and the compressor kicks in, the engine will intermittently do the same thing only more longer.
The check engine light does not come on or blink, and there are no codes storted.