very very wierd isuue guys..
 

Hey there guys, I am having a problem with my 1988 300e, yesterday i installed a basic pioneer deck, never having done this before i looked up all the color code of the deck and car wiring harness, then cut and spliced. Install went out the deck is now working and sounds decent. However, ever since i put in this new deck my lights flicker slightly (interior and exterior), my RPM needle dances to the bass...seriously, and the lights for my heater switches and all those on the center console no longer work. The flickering of the lights only happens once i turn the engine on? Could this be a grounding issue? BTW, i have a new alternator.
Any help would be appreciated as this is drivng me insane. Thank you.

Your understand that you've installed a 4-channel radio into a car originally wired for a 2-channel radio.