I had switched to an oil pressure guage that uses an electric sender, I had a mechanical guage set up but it made a noise i couldnt stand, now when i turn on the key it sweeps over to max pressure, when i start it it moves down to 70psi, witch is where the manual guage read when i had it in for initial start up, so at idle it stays there, if i rev the motor faster and faster the guage moves lower the higher i rev, i know my actual pressure is not fluctuating accordingly, as i kept the test guage on for awhile when i drop this new rebuild in, i somehow think its a ground issue or could it be wrong guage size wire? any thoughts? Thanks in advance

I suspect you have it wired backwards. pos to neg, neg to pos. Give a photo of it, brand and model number. There are thousands of oil pressure gauges.