Engine Surges while driving, Idles fine

[J_pete15]

    My Tracker Idles Fine but when I am driving it likes to surge or hunt. If I am on the throttle getting up to speed or off the throttle slowing down it doesn't do it, just in the middle. Almost like when there is just the slightest load on the motor it does it. Has been doing this for a while now. 
I have a manual switch in the cab for the cold/hot idle as that was the easiest fix for that not working. 
When the A/C kicks on it idles up auto like it should. 
I'm thinking it might be in the ECM? Anyone else have this problem?









93 Tracker 4x4 manual
89 sidekick motor