miss fire and popping back

[rizzle2181]

i have an 1999 expo with 4.6, i have a skip in it that i can't figure out. I've replace the pcv valve and hoses, spark plugs, wires, and both coils, I've even replaced the number two cylinder fuel injector and about to replace the other 7. but so far no luck with that issue. i also smell antifreeze coming threw my vents while the a/c is running but i don't have any leaks nor is the antifreeze getting low. i was told that the heater core is going bad which isn't a problem for me to fix seeing I've done several others for friends of mines, but any help would be very appreciated.

 

[docraymund]

Are there any codes? Try pulling injector connectors one at a time and note any change in rpm.

 

[rizzle2181]

ive pulled all the injetors and changed all the injectors and its giving me a misfire code on number 2 cylinder. it has a full tune up plugs coils i was waiting on the wires. ive even fixed the pcv valve hoses and elbows