Cylinder has spark but not firing..

how to eliminate the Intake from being a problem, with tools in your house or garage (I do a lot of trouble shooting at other peoples houses ) so not always having the right tool with me I turn to the mcguyver way. remove pcv valve and place a plastic baggy under it and put back in place, next remove the oil filler and seal it also, look at valve covers and seal anything that can leak vacuum from the crankcase also tighten valve cover bolts , next open baggy or vacuum gauge and place it on oil dip stick tube and seal air tight with tape or wire tie after removing oil level gauge. start engine and adjust idle to 2000 rpm for 4 min did the baggy get sucked in or out if in goes in you have a intake sealing problem and it doesn't make any difference if 8/4 are firing while testing if this passes the intake is not leaking then do what others have said and shim rocker shaft out .030 .shims at most mopar supply stores.