studders

My brother owns a 1997 Cutlass LSS that just recently had a new engine installed at 96k miles due to oil in the combustion camber. Anyway the car seems to hesitate during normal driving conditions and even stalls on the road. He called me from his cell because the car was studdering on him while he was driving in town and then all of a sudden just stalled. I went to meet him to see what I could do and drove it myself around a parking lot. The car studdered and stalled within a minute. My first thought was the fuel system, so he poured some fuel injector cleaner into the tank. The car seemed to improve a little at speeds 12-25 mph, but still studdered while accelerating. Went to pep boys to have them change the fuel filter, and seems to improve for the most part, still studders at high speed and heavy acceleration. I don't knokw how often your suppose to change the fuel filter, but my thought is that just needs another gas treatment due to the prolonged use of the stock fuel filter. Any suggestions would be helpful.

c'mon, no one has any advice or suggestions, I find that hard to believe. Someone please help.

Oil in combustion chamber and engine was replaced? hmm...
Probably the valve seals just needs replacement. If the PCV valve (located on one valve cover) has not been replaced, metered air/oil vapor by the PCV valve is not relieving the engine pressure. Instead the air/oil vapor from the engine due to pressure will cause the air/oil vapor to move backwards and out of the breather hose (located on the other valve cover). The breather hose is suppose to allow filtered air to go into the engine, however excess engine pressures will almost always let the air/oil vapor to come out of the breather hose and especially if the PCV valve is stucked closed.

Leaking valve cover (probably just need valve cover gasket) will leak oil and into the spark plug hole. Once you remove the spark plug and not cleaning around the spark plug hole before removing the spark plug will always let the oil go into the combustion chamber.

Water, oil, etc., around the spark plug hole will always cause misfire and cause your engine stutter and have no power. Make sure that the spark plug wires are not rubbing on the engine block or touching each othe spark plug wires. Use a tie wrap to separate the spark plug wires away from each other and away from the engine block.