Oil pressure problems??
 

I was driving my car the other night and noticed the oil pressure gauge was acting funny. At idle the pressure would be fine, about 3/4s of the way up on the guage. If I got on it or just drove at about 40 mph it would go way down. I thought it may be the sending unit because of the readings it was giving.The motor does NOT knock and the oil level is fine. Hopefully this isnt too hard of a fix. any ideas?

Could be the sending unit or the gauge itself. I've had a lot of problems with the stock gauges on my 90 GT, I think the ford pieces suck, even my sending unit in my fuel tank is shot! I'd say install autometer gauges is you really want numerical accuracy, if not, the stock gauges may still indicate increases and decreases, but the numbers might be off IMO.

This probably isn't your problem but it was wierd so I thought I'd share it. About a year ago my youngest one's Cleveland started doing pretty much the same thing. At idle it had 60 psi. When you gave it any gas as soon as the engine hit about 2000 rpm, the oil pressure went way down. I'm talkin 15-20 psi. I figured bearings so we collected all the stuff to do a bottom end job and when I took the pan off I found the oil pump pickup screen was covered with what appeared to be bearing pieces. Until I went to pick them off the screen. Ever wonder what happens to all those little pieces of silicon that get squished out from between engine pieces parts when you assemble a motor? Eventually they fall off and when enough of them fall off, they congregate on the oil pickup screen. to the point where they completely clog it off. I went ahead and replaced everything but, that was a first for me and definitely the last as well. I will NEVER leave anything more than a light film of goo on a gasket from this point forward.

yes but if its a stock motor you most likely have bearing problems. run a mechanical oil pressure guage from autometer and then take another run.

Could be a grounding problem; check your grounds and as someone else said put a mechanical gauge on it real quick and see if it still does it.
Good luck