Ok. I have a 94 Chevy Silverado with 4.3 v6. About 120,000 but always starts and generally runs fine except for this condition. When the engine is cold, and obviously running richer, it runs strong and accelerates good. But when the engine warms up, It's bogging under hard acceleration or accelerating from higher highway speeds range. Driving on highways is fine until the road starts to incline, then the engine starts bogging even if I give it more throttle. Eventually I have to push the pedal so far down, the truck will have to downshift to 2nd, even at 60mph. And even then it doesnt pull strong, but struggles. If I back off the pedal the engine will actually get more power. It's as though its leaning out, because even the temp gauge rises over 210 during this. Leaner = hotter. I've replaced plugs, cap, rotor, fuel and air filter, and 02 sensor. Ive looked for vaccum leaks but didnt hear any. Or is there a timing problem? Any suggestions?
much appreciation, Drew