What to do when mechanic says replacing oil pump may not fix problem?
I replaced the engine in my 92 Jimmy in 2015 with a Jasper remanufactured engine. It had a 3yr/100,000 mile warranty. In June 2020, the Jimmy started experiencing a problem accelerating especially when going uphill. The Check Engine light came on at least once. I parked it for a while and didn't drive it again until July. During that drive, the Check Gauges light turned on and off as the temp gauge needle fluctuated up and down. (I'd experienced that problem before with this engine, but I can't find what the problem/fix was in my maintenance records.) Anyway, I had the Jimmy towed to a shop that works on older vehicles. During the diagnostic test, the mechanic discovered the engine had no oil pressure. Replacing the oil pump would cost $1500-$2000, but he couldn't guarantee that would fix the original acceleration problem. What else can or should be tested before I make a decision on the oil pump?