Getting misfires when you accellerate and sometimes at idle. I have checked fuel pressure and is 55 with key on engine not running. Drops to 50 with the engine running. I have also replaced all three coil packs. What would be my next step injectors? Any guidance would be very appreciated.

 

Have you changed the plugs?

 

i had the same problem with idling engine going up and down. try replacing the "Idle Air Control Motor" which is located right at the intake manifold where the air intake plastic hose meets the metal part of the engine. the idle air control valve looks like this:

 

if that doesn't work, try cleaning the throttle body. that will help with idle problems. here is a good video on how to clean the throttle body air intake.
http://www.youtube.com/watch?v=Pc5qCuQLmFE

 

Have you changed the spark plugs and or wires?. you could have a bad or cracked plug.....or a bad plug wire.....If it does it when it is wet or damp out... for sure replace the plug wires.....(use the good delco platinum plugs and delco wires) If you have bosch plugs replace them with delco platinums. When you remove the plugs inspect them closely to see if they all look the same, if one or more is wet or carboned more than the others you can pin the problem to those cylinders, a new fuel filter, air filter and pc valve wouldn't hurt either. Replacing the coils first sounds a little extreme.... If you suspect the injectors use some injector cleaner......Usually when the iac and or throttle body carbons up you will get a stalling and rough running condition..
Good Luck