1998 Chevrolet Trailblazer Wont Car Over 30 Mph

have cat converters checked for failure.

have the fuel pressure checked as well.

Roy

1997 chev. blazer ls 4wd w/ 156,000 miles when you get to about 30-50mph it acts like it has no power and bogs way down to the point can't run over 30mph checked cat ok replaced...ignition module, wires, cap/rotor,pickup module, coil pack cked plugs look good ran scan shows po300 if not misunderstanding means multi misfire at a loss of what else it can be please help

check and see if you have a good ground from the block to the frame. and from the solenoid to the battery see if the cable is pinched