1997 Oldsmobile Bravada 1997 Bravada runs horrible

I have a 97 Bravada that has been having some problems, it currently is misfiring while I drive. The acceleration when this happens is almost completly gone. I took it to a shop and it gave a po300 gode along with a Mass airflow error. So far I have repalced the following:

mass airflow sensor
ignition coil
spark plugs
spark plug wires
fuel filter


I have been looking online and seen there are about 7 casuses to a po300 error code. I was thinking its probable the fuel injectors or the coal packs(not sure what these are any help would be great),

if anybody can help me out with this it would be great

Thomas