Chevrolet Repair: Oil consumption - no smoke, piston rings, consumption rate

Question
I have a 91 Chevy K2500 with the 5.7L. I am experiencing a problem with high oil consumption but I cannot figure out where it's going. My consumption rate is about 3 quarts in 250 miles on the highway at highway speeds. Not as bad when I go 250 miles around town. It doesn't smoke that I can tell - not even on the tell-tale valve guide seals when first started or sitting idle for extended periods. I've checked for leaks and found one small seepage at the oil cooler line but certainly not 3 quarts worth. I have had Chevys for almost 30 years and know quite a bit about their characteristics. I have checked the plugs and all look normal (clean light brown ceramic), and I would expect if it were burning the oil, there would be deposits on the plugs.
Another factor that may be important is that it seems to have a shortness in power- especially when coming up a small hill or powering onto the highway from the on-ramp. If my cruise is set say at 65mph and I come to a small grade, I can feel the pedal eventually go to the floor and be full throttle- downshifted and all. It's almost like it is gagged.
The truck has 101K on the odometer and I've had it just over 3000 miles now. I have never experienced this problem with any Chevy I have owned so it has me stumped. I've had many that had the typical high miles with the valve seals leaking or the rear seal or timing cover leaks so I know those from experience and I've checked that much of it. Not the true problem here. I am suspecting the PCV valve/system but the truck idles very smooth. I did note that the plastic pipe at the valve cover going to the TBI top tin is broken and there isn't an overly excessive amount of oil in that area- so I don't know if blow-by is a factor either. Maybe between us we can come up with checks and tests to perform. Thank you in advance.

Answer
Hi Jay, There is only one place to take in oil at that rate. Through the piston rings. I would first check the PCV valve and the vacuum going to it. The TBI units plug up on these and no vacuum will get to the valve. You will need to remove the TBI unit if this is the case. Now you can clean it out. If the PCV isn't working it can cause high pressure in the crankcase and push the oil up through the rings. If the PCV is all good you might want to try a crank case cleaner in the oil. The part store sells this product. I thinking your going to need a set of rings but you need to try this stuff first because you never know!!

Have a Great Day  

Mark