It does seem like a ground. Unhook the tps connector and use a DMM and set it on ohms and ground one lead(to battery - post) and put the other on the ground on the tpd connector. I do not recall the color of the ground wire on the tps right this moment, just look in your manual.
This was acouple days ago. Took a pic of friends blazer before lifting it, but you get to see the snow on the ground. Im living in laramie, wy @ 7100 ft
I drove the other day when 5 inches fell out in laramie, WY (6 degrees also) were Im going to school with khomos and it was hell. I would say get some Blizzak's and then some sand bags in the trunk. You will be ok.
I would never put forged pistons in a stock block unless I was doing a basic rebuild that required to bore alittle to clean the bores up and got them for almost the same price a hyper. You will crack the block before you run into an piston problems with a good tune. BTW Chris on TM is making...
The first pull was most likely with a extremly conservitive tune. The second pull they probably added alot of timing and some boost too. Its a marketing thing they don't and won't tell you everything. But it looks like deal, but I would make my own kit.
Take a piece of vacuum hose or a stethoscope and put it up to your ear and the other end to were you think the sound is coming from. You will be able to tell dead on.
The driveshaft is out of balance. Try unbolting it and then putting it back on it a different position. It could be the reason. Try this first and see if it fixes it.
How cold of weather are we talking about? The PCM is designed to dump extra fuel at a cold startup. It helps because fuel does not atomize as good when cold.