my oil pressure drops to 0 when I stop or idle down. It drops off instantly. seems to operate fine above 1100 rpm, but the gauge goes from 30 psi to 0 when I stop. usually doesn't do it till it's warm. The truck sat for several months while I was out of town and when I got back the problem went from every once in awhile to frequent.changed oil/filter(delo 400 15-40) could it be the oil pressure sending unit?

98.4 2500 ctd 185000 miles

 

replace the sending unit also if its oily, clean the harness end with brakeclean

 

Yup, that's the first place to start.

That's usually the problem.