My 88 Classic ran fine one day then the next it was like it had lost 100hp. I changed the fuel filter and the compression, plugs, plug wires, cap, roter, air filter are fine. It starts and idles fine. There is a sound like a combination between a vaccum leak (didn't find one) and a loose belt (not one either) that occurs only while driving. I know my way around under the hood, but am kinda new to quirky British stuff. Any help would be apperciated.
thanx
don j

 

here are some thoughts. do both wet and dry compression tests. if a/c on your vehicle check the compressor, check the timing. vaccum advance, throttle body function. This will be a strange but I have seen it. pull the wheel, and check the brakes, including the parking brake. another strange one bad gas or blockage in the gas tank. fuel pump. If fuel injected, clogged injectors, or injector rails. I own a disco and am going of the top of my head based on previous experiences. I am also going on the idea that other than the sound you descriped, the engine runs smooth, just has no power, and the motor will rev up like normal, while in park. Check for some type of restriction in the exhaust system. Air in and air out make power as well as the other things you have already checked. I hope it will give you some new ideas, it sound like you are heading in the right directions. Gotta love a rover. duboff