I'm interested to know if the heatsink helps you out any. Are you using an enclosure with your mpguino? When I get mine back I'd like to find out how to put it in an enclosure with a temperature-controlled fan in the back, perhaps in conjunction with a heatsink.
I'm not sure about the VSS signal oddity either. You could take a look at this thread:
http://ecomodder.com/forum/showthrea...ates-4236.html