SWR high, but...

Shorten it so it will be more stable.

 

Is the antenna and all its parts (coax, connectors, etc) new, or did you pick it up new? Too many variables right now to diagnose it, let alone blindly cutting the whip and finding that wasn't the problem. Try the antenna on another metal-roofed vehicle first. Also, was tbe radionew, or has some yay-hoo been inside and fiddled with random stuff? 73

 

My first thought is, it sounds like its not grounded. You are grounding the antenna when you touch the mount. But its hard to say
Is swr high on all channels? 3+?
Do you have an amp in line?
Did you use a teflon isolation washer between the antenna and the mount?
Is that pic of your actual install? If so, that isnt a wilson 2k..
You may have to do some continuity testing, do you have access to a multimeter?

 

Check for continuity between the mount, and the mirror arm. It looks like the mirror arm is painted? Or coated? The mount may not have an adequate ground.

 

are you in a fiberglass truck, ie cascadia ect, that could cause it lack of reflect