I had trouble with one of those a few years ago. I can't remember the exact symptoms but it would stop running after a short time. I finally found a bad connection in one of the wire harness plugs. It showed signs of overheating(plastic was melting) and I actually had to run a bypass wire around that pin on the plug. The harness plug was somewhere in the back by the control panel. Did you check all the harness plugs for bad connections?