I have a 2001 and after sitting for a couple days it now will cut out around 2k or 25-30 psi with comp box on. I shut the comp off it runs fine. Maybe wire tap?

Any codes?  

Wire tap or stealth plate?

Wire tap

Might be half your issues. If the wire tap is weak and not seeing a good 12V connection then your power will become weakened as well. I going to assume you use a scotch-loc connector for a wire tap too? Those are known for cutting through the wire and leaving barely any thing connected. Then with a bit of water or road salt the connection gets worse.

As for cutting out you might want to verify your AC noise from the alternator. If its excessive it could create weird problems. Double check the master ground on the passenger side battery as well. The ground is the one attached to the battery tray.