Here's the official instruction sheet:
http://www.isspro.com/downloads/inde...Rev%20C%29.pdf
The most common issue I see is where people don't squeeze the pliers tightly enough when pressing the connector into the tool. It could also be that the connector terminals are getting spread open (please PM me your address and I'll have a new connector sent). Also, if you haven't already done it, please remove the bare copper wire from pin #6, and cut it flush with the outer sheath. We have found that this wire tends to loosen up, then cause noise with its intermittent connection. That wire is not necessary, we added it for an OEM customer that wanted it to pass a ludicrously high EMC/EMI standard.
If the items above do not solve the problem, it could possibly be an intermittent connection inside the thermocouple. How old is the gauge?
__________________
ISSPRO Engineering Manager
Under Construction: 1999 Chevy Pro Stock Diesel Pickup
LBZ, GT4202R over GT5541R, sponsored by ISSPRO and Chris Alston's Chassisworks
95 F350 CC DRW, Intake, exhaust, chip, injectors, locker, gauges
00 Jetta TDI - tunes, clutch & gauges
And a bunch of gassers