Random revving and acceleration

[JSinAlaska]

So my work truck is a 2000 GMC 3500 with a 6.5. When it's warm, you've been driving for a while, such as plowing or idling, it'll randomly accelerate, and rev up. It's quite scary actually, especially if you're sitting at a light, plowing (our plow truck) or driving through traffic. It's like something is sticking.. I've heard of engines cutting out, but not accelerating on their own.. anybody have any ideas what that could be?

 

[argve]

PMD (pump mounted driver) is going bad. A guy here at work just had this same problem on his 2000 6.5TD just a few weeks ago.