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
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2 answers 1 comment
ANSWER by , March 05, 2011
There could be injector problems, could be intake air leaks. Try the plugs and wires first.
COMMENT by , 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 , 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.