What would cause so many cyl. to misfire. on 1997 Ford Aerostar

I took my van in to a mechanic because is was jumping and jerking. He told me my head had a hairline crack. I had no water in the oil and was not over heating. I went to NAPA and got a printout of my codes. It told me cyl. 1,2,4 were misfiring. I am changing the plugs and wires tomorrow.Is there anything else that can cause the misfiring?

by in Price, UT on March 05, 2011
2 answers 1 comment
ANSWER by on March 05, 2011
There could be injector problems, could be intake air leaks. Try the plugs and wires first.
COMMENT by on March 05, 2011
Thanks for the reply. I 'll see how it runs tomorrow ,and go from there if it that does not work. Thanks
ANSWER by on March 05, 2011
Some 4.0L OHV engines of this vintage did have cylinder head issues. But the symptom would be more about coolant consumption. Also, misfire on 1, 2, and 4 means that both cylinder heads would be in question, not just one. Definitely start with primary ignition components - plugs, wires, and then recheck.