Erratic Gauge Readings

[kmcypress]

Hey Guys. I've got a painless wire harness that i've installed along with omega gauges (mechanical). I'm getting somewhat erratic gauge readings and I was hoping I could get some help as to a solution. The oil pressure and coolant gauges are reading slightly higher than normal. However, the problem gets even worse after an extended time of driving and/or in conjunction with my light switch. they will jump up/down accordingly with the switch. here are two videos of the problem

https://www.youtube.com/watch?v=wyq18XpvB6U

https://www.youtube.com/watch?v=lJ7KQbl03js


i'm guessing its possibly a voltage issue. do i need like a secondary voltage regulator? do they make one that simply splices in?