2003 Jeep liberty renegade 3.7 v6 P0306

i keep getting P0306 codes (cyl. 6 misfire) on my 3.7l and it doesnt like to fire up it will crank and crank if i let off and crank again it will fire right up, then sometimes it will spit and sputter then fire up like it was carb'd. if i take a drive and go shopping and come out it does the same thing crank crank then fire up in like 10 seconds or so.

i changed the plugs from the factory NGK V-Power to Autolite Copper it didnt help swapped the #6 coil to the #3 coil and it wouldn't start swapped the #3 with #1 and it started but ran rough so i bought a new coil pack for it and replaced the #1 which was originally #6 (hence the code) and now it is doing the same thing i am still getting a P0306 (cyl 6 misfire) code.

when i pulled the plug on #6 it had some oil on the top of the threads where the socket would grab the nut, but the rest of the threads and plug were clean normal looking color.

a friend said it may be a cam/crank position sensor.

does anyone have any idea as to what it may be? i only have the powertrain warrenty cause it is certified preowned and they want $45/hr for diag. i didnt do a comp. test yet

if you need more specifics lemme know

45 dollars for a door rate is probably too low to employ techs competent enough in driavability. Try using the correct spark plugs for starters and have the compression checked. I have seen some camshaft failures on the 3.7's and injectors plugging up. You could try switching the injector to another cylinder and see if the code # changes to a different cylinder. Assuming the compression is good. A flat cam lobe won't always show up on a compression test. Cranks sensors are a common enough failure on those engines but they don't normally give just a misfire dtc and they can break off in the engine quite easily if you're not careful. I've fixed enough liberty's too know they aren't my favourite Jeep!

comp test showed 150psi +/- 2-3 across the board couldnt do a leak down as we dont have the proper equipment the comp checker holds the pressure.

ill see if i can get the injector off and swap it to the opposite side Cyl #1 so it will be easier to change if that is the problem

plugs have around 2000 miles on em, and some oil on the threads of #6 only, rest of the #6 plug is normal the other plugs look a little ashy grey in color on the tip and contact center diode is bright white.

it since has started up fine but i know there is a problem somehwere

if you have a noid light stick on the injector plug to #6 to be sure it's even being pulsed by the pcm before removing it and switching it.

yeah dont have one but i could rent one i suppose or buy one they're like 40 bucks for the kit