So far ive changed plugs ,cleaned maf and throttle body,and changed duel pump.so is my next part the opti? If so what one should i buy and how do i change. Also which water pump? Im thinking acdelco for everything

 

What are the symptoms of the car? What is it doing besides throwing codes and ses?

Brian

94 Z28 4l60e. Reworked heads ported and polished. Cam 3" catback flowmasters. And common bolt ons.

Any help or advice i give is my 2 cents and is based on my experience with the F-Bodies. As always seek professional help for certain problems.

 

Its idiling really ruff loss of powere aswell

 

The ol' P0300. Random, multiple cylinder misfires. You've changed the plugs, how about the wires?

 

By the way, the blinking SES lamp means the misfire was severe and often enough to possibly damage the catalytic converter(s). I would try to get this fixed soon, unless you have no CATS installed.
I would also try to use a scantool that can narrow down the misfires to particular cylinder(s). A Tech2 can do that as can some others. Also, my free OBD2 scan app can show the misfires by cylinder: Free OBD2 scanner software - Firebird Nation

 

Wires are 8000 miles on them inspected them looked fine also started it up at night and no sparks

 

Can i run without cats ? I will get ridd of if possible

 

Did you check the fuel pressure after changing the pump? Did you check the fuel pressure regulator?