1997 Honda Civic Highway surge irratic idle.

Engine Mechanical problem
1997 Honda Civic 4 cyl Front Wheel Drive Automatic 100k miles

Hello, my Civic Has idle surge after it has warmed up. It started after the car had been sitting for about 5 months. Turning the AC all the way up seems to stop the surging but it still has a high idle. It also has highway surging. It feels like the car will only speed up or slow down, not maintain a constant speed when the AC is off. There is no check engine light. I've bled the cooling system and cleaned the IACV as well as inspected hoses and intake for vacuum leaks. So. What do ya think. Appreciate any advice!