Oil gauge fluccuates,while driving. Indicates zero when stopped at traffic light, then gradually moves up as accelleration increases. The only time I get a normal oil pressure reading is at start-up. Dip stick indicates oil level is correct.

have the oil pressure checked using a mechanical pressure gauge
most likely a problem oil pressure sender unit or broken wire

Low pressure when at idle, after the engine has warmed up and the oil has thinned, indicates that the oil pump is worn and needs to be replaced.

If your oil is full, it's most likely electrical. If it's not electrical, then it's most likely something like a crack in the pickup tube, sucking air if I had to guess.

check to see if fan stays on all the time
if not i have seen thermostats put in backwards
the thermostat is what holds water to the block to warm
to op temp then open to cool

You have a sensor that controls this. It is a temp sensor. It could be called something else, but it is a sensor that measures your engine temps. It would shut the vehicle off if it is not working properly.

Two things could be low on oil, or the pick up screen to the oil pump is starting to get clog, I have seen this a few time's on this type of truck here at my repair shop.

They go gradually. the problem is the oil temp switch. they are located onthe back of the engine, in the middle. about 3 inches long

perform a master oil pressure test. this is done by removing the oil pressure sending unit and installing a oil pressure gauge. if the reading on the test gauge is ok, the sending unit needs to be replaced. if the pressure reads low on the test gauge, there may be excessive bearing wear or you may have worn valve guides. good luck!

u ***

spray a samll amount of either near each vacum line connection if the rpms go up theres your leak!!