I have a 02 blazer with a 4.3 , 2wd. My problem is i have a misfire just when it idles with the a/c off sometimes it will make the check engine light flash. and its worse at times. But when i run the a/c it runs fine no check engine light idles smooth. i have changed intake gasket, new distributer, plugs, wires, fuel preasure reg, crankshaft sensor. any suggestions

 

A flashing CEL means that the PCM has detected a potentially harmful misfire. Have a read through THIS THREAD. Are there any other codes present/pending in the PCM?

What brand parts were used? Aftermarket caps & rotors have been found to not work correctly out of the box for many members.

What made you replace the CKP sensor?

Did you set the CMP retard after the new distributor was installed? With the setup of the ignition system used in these trucks, for accurate spark control & to extend the life of the distributor drive gear, CMP retard must be set to zero degrees using a scantool to monitor the value while you move the distributor in the hole through the lower intake manifold.

Have you done a CASE relearn? A CASE relearn or crankshaft variation learn procedure sets the precise variance between the actual ignition events and the readings from the CMP & CKP sensor readings. When replacing any one of the components that would affect this variance, a CASE relearn should be performed; especially if either the P1345 code is present or a misfire is present.