For what its worth, I had the same problem with my 98. I changed the Oil Pressure sender, but it didn't solve the problem. What I found was the problem was sludge build up in the engine. I changed my oil at the normal interval, and instead of using 5 quarts of oil, I used 4 quarts of oil and one quart of Marvel Mystery Oil. After about 60 miles of EASY driving the problem went away. I changed the oil after 500 miles and it was thick black and dirty. I again used the 4 quarts of oil with one quart of MMO and drove the truck normally for 3000 miles and changed the oil again. The problem never returned and my oil ismuch cleaner now at the end of 3000 miles using the 4 to 1 ratio of oil to MMO.
Dave
Sunday, March 16th, 2008 AT 5:38 AM