Hi all. Just joined this community as it seems very active and I always liked listening to Car Talk on the radio. Looking for some advice on a 96 Isuzu Trooper with a 3.2l SOHC V6 and manual transmission.
Recently it has lost a dramatic amount of power, so the truck has gone from pretty slow to barely drivable. It cranks up instantly and idles perfectly. Everything feels normal taking off from a stop, except power does not increase as the engine revs, it might even decrease. Between idle and maybe 1500rpm it feels torquey and responsive, then just bogs down past that. Therefore it takes extended wide open throttle just to get to 45mph and I cannot maintain speed up inclines in any gear. Getting to 60 takes about 50 seconds on a flat surface. The Torque ODB app calculated 47 peak horsepower. There is also a rhythmic surging sensation under full throttle when it’s hot.
Other than having barely any power, I cannot find indication of a problem. No check engine light or codes. Dry compression is 150-165psi on all cylinders. Spark plugs look great. Fuel trims are normal not indicating a rich or lean condition. Just replaced the fuel filter yesterday. No obvious misfiring. Vacuum readings are normal and if I rev it to 2500 it stays there no problem, which I think rules out a clogged cat. I ran it with the MAF, MAP, Intake Air Temp sensors, and the EGR all disconnected individually with no improvement. It seems like poor acceleration would have to be an air or fuel supply issue, but I think my troubleshooting has ruled out both. Is there anything I’m missing here? This really has me stumped as the truck just isn’t showing any other signs of a problem. Thanks in advance for any advice!