Mysterious electrical issues please help

I am a new boat owner and new to this forum and love the helpful topics that are on here and im hoping that some of the guru's on here can help me. I have a fourwinns 225 sundowner with a 5.0 gi Volvo Penta wit a cobra sx outdrive. My issues started a few weeks ago and have worsened since, it started with my gauges going on a blitz all at once while the boat was on the go the boat would work fine but the gauges would all zero out and when I put the drive in neutral it would stay at fast idle until I shut the boat off and restated it and it would work fine for awhile again. Then last weekend the gauges would go wacky and the boat would start to stutter at about 30 mph and the engine would start making a rotten egg smell weird. Now as soon as I start the boat it idles fine and gauges work until I engage the drive and gauges go to zero and flash does the same even when drive is neutralized and when I rev the engine gauges do the same. I have endlessly chased wires and have checked all connections and added di-electric grease to all of them. Can anyone one here please help me thanks.

Re: Mysterious electrical issues please help

Do an engine running wiggle test of all connections, under the dash, the engine compartment, and all the wiring running between them.
keep an eye on the gauges, they will tell you when you find the problem.

Re: Mysterious electrical issues please help

Thanks for the reply I will try that tomorrow, will bad grounding or loose wires cause the engine to act up also by sending bad singles to the computer ? Also I noticed that their is a galvanized wire running from the gauge harness is this the same wire that goes to the outdrive for grounding. Thanks