I will try that. It also surges when just starting it up and it's in park.
ok, can I just go and come back to this site?
Could not get it to act up, of course drove perfectly! Usually when it has sat at work for 10 or more hours, or overnight I have problems. I will try tomorrow. I also think there might be a vacuum (?) leak somewhere, but no one seems to find it. Could that be a reason on the start up?
I think you're right about the trans, because when it's surging, sometimes there's a "thunk" from under the front end and it acts like it wants to find the right gear.
truck is back in the shop, they are checking the tcc solenoid. haven't heard from them, yet. I'll let you know. The surging did stop temporarily when I hit the brake pedal. Hope you were right.