Engine hesitation

I checked the MAF and it checked good. Hz findings were what seemed appropriate. So that leaves the MAP sensor, which was also original. Test results looked a little shy on the meter. So I changed it with no improvement. However, it was 21 years old. Scan tool showed intermittent misfire. Unplugged the MAF, and bingo, the problem was gone. One mechanic on the net had stated the MAFs will sometimes test fine, and still be bad. This seems to be the occurrence in my case. New MAF sensor is on order. There also was never a MIL lamp until I unplugged the MAF and drove the vehicle. Plugged in the MAF, and hesitation returned, MIL lamp went out. Thanks for all your suggestions. Hope my info helps you and others. Keep up the good work!

After replacing the MAF, MAP, TPS, EGR, pump and filter, addressing a possible grounding issue for fuel pump, which I knew some of these items were bad, very old and going bad, or not thoroughly reliable during vehicle use. I began testing things with a little confidence that I was going in the right direction. (Still no CEL, and scanner shows MAF problem) The vehicle still had a part throttle stumble like there was a fuel delivery issue. However, the vehicle had tire chirping torque that was never there before. As we know this is very bad, and must be corrected. Obviously fuel trim is wacky. Also had unusual power supply at MAF. Replaced ECM with a re-flashed item matched to my VIN. This helped immensely, but the stumble was very slight and barely evident. After driving vehicle about forty miles, vehicle does not stumble and fuel trim seems correct. I suspect there was a fuel pressure regulator problem that corrected itself, or the ECM finalized some adjustments. The vehicle runs very well now.