Jus did the oil/filter chang on a 2003 Chevy Silverado 1500 4.3l! The oil pressure drops down n have to shut the truck off and also the engine starts to run hot when this happens!
Have you checked the oil level in the engine?
I'd check you got the right filter on it, the oil filler cap is back on tight, and, as ytlas suggests, oil level.
Both of the answers previous give to you are good ones check to make sure you have the right filter on and the right oil it should be 5w/30.
Looking for a Used Silverado 1500 in your area?
CarGurus has 155,182 nationwide Silverado 1500 listings starting at $1,395.
Search Chevrolet Silverado 1500 Questions
Chevrolet Silverado 1500 Experts