my blazer is misfireng when its cold then runs like dream after it warms up and i restart it. when its in park the oil presure gauge is normal but when i put it in drive its starting to jump up and down i havent the slightest clue why these problems are acuring iv looked over every thing i can think of and came up with nuthing anyone have any thoughts or ideas what coulod be cousing the cold misfires and the oil presure jumps?

 

The gauge problem sounds like a loose connection or potentially a break in the wiring.

Are there any codes present? Have you done any routine maintenance (plugs, wires, cap, rotor, cleaned the MAF/EGR/throttlebody)?

 

The running rough when it is cold could be due to an inaccurate temperture sending unit for the ECM. (The one by the water pump inlet at the front of the intake manifold). The erratic oil pressure reading could be due to faulty gage. I had the same issue but first i checked my oil pressure with a mechanical gage to verify the actual oil pressure. My pressure was normal so I pulled an oil pressure gage from the junkyard and installed it and it works perfectly.