I rerouted PCV system out of air cleaner, new air filter, and went through 4 bottles of carb cleaner with no help. I disconnected exhaust with no help, there is no cat converter. Fuel filter and fuel pump are new. Plugs are in good shape, timing checked fine. Several vacuum hoses are missing as are parts of the emissions system, but important ones like vacuum advance have vacuum and no leaks. Slight tapping, worst around 2000 RPM, gets better with premium gas so I think it's spark knock but might be a stuck lifter. Lots of carbon in the exhaust.
I haven't had it compression tested, if it were bad rings I would think it would have gotton a little worse over the almost 2 years I've driven the snot out of it, but it is no worse than the day I bought it. It uses a litre of oil with every 100 litres of gas (3-4 fillups), and I suspect a rear main seal leak as it's dirty and a common failure in this engine.
I was told the engine was recently rebuilt when I bought it, so if the rings are shot already then I was lied to, thats why I'm suspecting carb or exhaust problems. Am I just having problems facing the fact that this engine is dead or is it possible the problem could be one that something short of a rebuilt will fix?
If this engine needs a rebuild I'm going to get a 92-95 camero 3.4 to swap.