Well, that kinda sums it up, doesn't it? So, I THINK we can somewhat safely assume that the issue here is a defect in the Cruise Control. Only problem is, there is no cruise control. What I mean is, the "cruise control" is an application that runs in the PTCM. So just replace the PTCM and all is ok, right?

Well, even THAT expensive option may not fix it - because we don't know if the PTCM is doing this because of bad data coming from a speed sensor somewhere, or maybe the cruise switch assembly (referred to in the manual as the "speed control switch".

The brake pressure switch tells the cruise to disengage - so that would fix it if the cruise is not dis- engaging after being set. As to the switch assembly, well, read on.

The ACEL/SET line coming from the "Speed Control Switch" (I assume that is what is meant by "Cruise Control Assembly -since there isn't such an assembly in the car) COULD be the issue. IF that line is "high" at the input to the PTCM, then the PTCM is doing what it was designed to do, it is accelerating in command from a defective switch.

By monitoring that input, you could 'see' the line go high and when it does, the car would take off on you. But it would be hard to watch that line with a meter while driving. But you could CUT or DISCONNECT that line at the PTCM and see if the car acts up. If that ends the problem, then I would change the switch assembly.

If you are going to troubleshoot this yourself, you really need the service manual. I'd suggest you download it from this forum and start reading. Page 8P-8 of the SRT manual is what I am looking at (well, the whole chapter, but the diagram is on that page).