It accelerates fairly well up to 3k in every gear fine then either maintains speed or even slows down as the rpms go up. Yet, the engine keeps revving up (along with tach). When going up hills, it is chugging to make it up, and loses speed, even if i downshift. The clutch feels good, <15k on it. I replaced the fuel filter, no change. Engine is stock. I've searched around this site for and help but nothing helped. Fuel pump works, but haven't checked the pressure. Never hard to start. Any recommendations or ideas? Thanks.