To take it off the table I would get/rent a compression test gauge.
A cylinder needs 3 things to fire
1. spark, at the right time
2. fuel, mixed with the right amount of air
Spark and fuel issues can be intermittent, compression is either good or bad, very very rarely can it be intermittent, so once tested it can be taken off the table of possible problems or it is the problem.
Remove all spark plugs FIRST
Then test each cylinder's compression, write down results
Throttle needs to be propped open, foot on the gas pedal when cranking engine
170-180psi would be expected for 3.0l at sea level
But that isn't the point of a compression test
Since there are variables in the test procedure the point of the test is the comparison of all cylinders to establish an average and if any cylinder is more than 10% away from that average, higher or lower.
To average, don't use the highest or lowest cylinders, add up the 4 remaining numbers and divide by 4, that's the average compression, say it is 175, then 17.5 is the 10%, so 10% range would be 157.5 to 192.5, cylinder falling outside that range would indicate a problem
If one or two cylinders are lower by more than 10% then retest them but add a teaspoon of oil to each, via spark plug hole, and then test.
The compression number will go up, but by how much will tell you if it is the Rings or the Valves that are the issue.
If #1 has a compression issue then you can stop wasting time on other issues, i.e. spark and fuel.
Also have a read here: http://www.therangerstation.com/foru...96#post1510596
3.0l TSB is posted there about misfires