Headlights, interior lights, gauge lights, all my lights are flickering. Installed a new battery and did not fix the problem. Positive and negative cables are clean aswell. Ground issue? Any ideas, thanks guys.

 

Presumably this only happens with the engine running , and when the engine is off the lights don't flicker ? If so , when my car did that it was the alternator . A quick test for this is to unplug the small (2 wire ?) plug from the alternator with the engine running , if the flickering stops (lights may get a slight bit dimmer because your stopping the alternator from making power) it's a very good indication your alternator is the cause .

 

Everything flickers the same with engine off and engine running also the speed of the flickering doesn't change when accelerating.

 

Ok so since it's not engine running/not running related , yes you do likely have a bad (loose & arcing) connection somewhere . Shouldn't be too hard to find since it sounds like the whole lighting system is affected . The "backyard mechanic" way of troubleshooting this is to start wiggling wire harnesses to see which one makes a change in the flickering , or you could go "high tech" and break out the voltmeter and start looking for large voltage drops across the various harnesses/connectors the power passes through on it's way to the lighting circuit(s) .