I have a couple of issues that I need help with. We came up to the mountains where it is 50 degrees in the morning and I have to plug in my truck to get it started because my glow plugs are not doing well. My GPR is new but I noticed today after I got it started the GPR was clicking on and off until it went off completely after the 2 minute cycle. Anyone come across this? I'm thinking bad ground or relay.

Also, I have a vacuum leak at the a/c controls so that when I start the a/c I can feel the truck adjust idle until the vacuum sucks the connector at the back of the control panel tight. I have also noticed that my mileage has dropped by about a gallon per mile. Think these have any connection?

 

a vacuum leak wont change the idle, the change in idle is most likely the compressor kicking in

 

The idle fluctuates up and down when it comes on. If I'm driving and turn on the a/c the rpm's will fluctuate noticeably until the vacuum builds up.