Is your PCV valve plumbed to a pipe that inserts into the 3-4 intake runner? If so, then check your PCV valve and hose to make sure there are no cracks anywhere that could draw air. Small vacuum leaks from either of these could make for a misfire. Once the engine gets up to speed, the leak becomes too small to affect the air-fuel ratio.
There is also a possibility the PCV valve is not the correct application (could have been packaged wrong) and is drawing in too much air. Double-check it. They usually have the part number stamped into the side of the metal body. A valve for a big block chevy looks almost identical to a late L6 valve and will pass too much air.
------------------
David
newbie #4153
