Engine Performance problem
1996 Chevy Silverado V8 Two Wheel Drive Automatic 151000 miles
Ok, my problem is this. When I get my truck up to about forty mph and am cruising along, the motor starts to surge. It will jump from about 1500 RPMs to 1700 RPMs. I have changed out the speed sensor, the throttle positioning sensor, fuel filter, mass air flow sensor, ran injector cleaner through it. All plugs and wires have been changed as well as cap and rotor. So I am at a loss here. Someone told me it may be injectors going bad or maybe the fuel pump (which I did a pressure check on and was getting 50-55 psi). I was just wondering if you have any advice that might help?
Could be caused by the following below
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)
Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include: Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires