1993 Suburban dash problems

Hey everyone. I just found this site while looking for answers to my Suburbans problem. I look forward to reading what you guys have to say. It looks like alot of you are quite experinced. Which is odd considerating how great and dependable a vehicle Chevy produces.

Anyways, my 1993 Suburban 4x4 is having problems in the dash. As near as I can tell the tempature guage is consistant and accurate. My fuel and oil pressure however do not appear to be the case. When I set at idle the two guages will set at a normal setting, then jump up about 1/4 to 1/2 a guage distance. Sometimes they set for a couple of minutes then drop, sometimes they straight up and back down. This will also happen while driving but does'nt seem to be as frequent. I did'nt think it likey two guages, or the oil and fuel pump go at the same time. I'm hoping it's something simple and not electrical. There's a shortage of elcetrical shops in the area and the local dealers are rip offs and hack of mechanics. Also the tachometer reads low, at about 350 rpms at idle. But I think that's a seperate issue. I get no warning lights and it's just irritating, plus I figure the guages are there for a reason they might as well work. Thanks for any advice or experiences, and looking forward to reading and posting here.

Here's a suggestion.Check and make sure all grounds are clean and secure.Not just the ground from the battery to the block, but also the grounds that connect the block to the frame,frame to the body and there maybe a ground wire on the thermostate housing mount bolt.Poor grounds can cause all sorts of strange electrical problems.Hope this helps.
chuck's