Van slight surge going up hills...IDEAS?

[Hoags]

98 Montana, 125,000 miles. for a long while now when I drive the van up a long steady hill in high gear at a speed between 45 & 65 MPH the van will surge, it's not a bone wrenching type of thing in fact it's hardly noticable. It will quit when I kick-it to down shift and continue to pick up speed. It almost feels as if it doesn't know which gear it wants to be in. I can't tell if it is a problem with the tranny or with the fuel system. I have changed the fuel filter and had a flush and fill done on the tranny. I regularly use fuel injector cleaner and usually use plus or super grade gas. It does not seem to be a real problem and I don't suspect it will become one since it'sbeen going on for a while. It is more of an annoyance than anything else. Does anyone have any ideas? With my luck... it will turn into a major issue.
Thanks!

[GTP Dad]

The torque convertor solenoid is not releasing properly when you ask it to. Does it stop it stop this and the car picks up rpm if you touch the brake? If so that is your problem. I have the same problem on my GTP but haven't had a chance to get it worked on. It will cost a few dollars to replace at a tranny shop but shouldn't be too expensive.

[Hoags]

GTP Dad, Thanks for the input. I haven't noticed if it stops when I but on the breaks but I'll give it a try tomarrow and let you know.
Thanks again,
Hoags