delete

 

Do you drive on rocky roads (could be some of that noise is a rock stuck in somewhere) Are you burning any extra oil? Are your brakes up to par?

I had an early 90s lumina and had to replace was either the camshaft or crankshaft sensor (it was some time ago) It was above the oil pan. In any case the sensors can sometimes cause wierd issues like hesitation during acceleration had a bonneville that did something similar and again it was replacing the sensor that helped out.

 

Well my edit got lost in cyberspace but you already answered the questions about sensors.

What about your fuel preasure? Have you ever replaced the fuel filter?

 

If I remember there should be a filter on the fuel line along the frame line I am not possitive because some cars have taken to putting the filter in the tank with the fuel pump. Also if you you only replaced two injectors maybe the other old ones are having a problem keeping pace with the new ones.