How to ground PDC?

Hi guys, so I brought my cuda over to a guys house who has a scanner (snap on 2500). The scanner had trouble communicating but eventually did. Set the fuel sync. However, I was only able to get the scanner to tell me if sync was OK or NOT. The scanner stayed on zero and wouldn't let me dial in, I thought it would give me +/- readings but for some reason would not. Also, distributer was REALLY difficult to turn when engine was up to full temp, weird...any thoughts?
Test drove the car and ran/shifted great for ~3 miles, then pulled into a lot, put it in park and started sputtering/died.
No new codes.
Other odd thing was I received two coolant temp readings from the scanner (my year has the two coolant sensors). One reading was 203F assuming from the computer sensor, and got another reading of ~88F on the other scanner coolant temp. The second coolant sensor (single pin) I have is going to a aftermarket guage. I did not expect to see a second coolant reading and ideas why?
I'm still left scratching my head, thinking the aftermarket TPS I installed could be bad and I may throw a part at it again.
Any thoughts are appreciated!