My 2000 5.4 4x4 oil pressure light and gauge have been coming on when starting cold ,if I restart it a few times the light goes out and the gauge goes up when it is warm all is good. How big of a job is it to change the sender as I am sure this is the cause of the problem

 

the sendor is somewhere on the side of the oil filter mount area.. also, it it winter, how thick of oil are you using? the gauge is not an actual measurement, it is a switch that kicks on at 8 psi. If you have 6 psi for example, it will read zero. Cold weather and thick oil will do that, as will a bad sendor.

 

I am using 5w30 and it is about - 10 . I have always used 10w30 and never had a problem even at -25

 

Looking from the drivers side, it is just to the left of the oil filter towards the front of the engine. The wire runs right over the filter on my 01.