My 1989 Formula 350 Firebird, which has been running great for years, Is all of the sudden burning oil. It blows out big blue-white clouds, mostly at startup and acceleration. It is not burning antifreeze, and it can be hard to start. The starter will hit it, HARD, and it won't turn over. If you hit is several time, or hold the key in start, it will work past it and fire up. (I know, very bad for the starter). It doesn't act like it is missing a cylinder. A GM mechanic suggested the intake manifold gasket, saying that when the piston is down, it is drawing oil into the cylinder, which it must then compress to turn over. I wanted to know what you guys think, and if you have ever had this kind of problem before.

 

Has the gas mileage changed lately?

It sounds to me like an overly rich condition, but more than one defect causing it at different times. A leaky injector will cause the hard starting, and a bad O2 sensor can cause the other. Your description of starting sounds in fact like one or more injectors is leaking enough that one or more cylinders is filling up with gas, and getting "hydraulic-ed" since fuel is incompressible.

If you haven't changed the O2 sensor, it probably needs it anyway; that should be a part of a tune-up, maybe not every time but every other time. You can check for injector leak-down with a fuel pressure gauge on the fuel rail, after you turn the car off. It should hold pressure for hours.

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"So many Mustangs, so little time..."