Other things that would cause misfire?

[FourBinLabs]

Ok, Vehicle is a 2000 Mercury Mountaineer 5.0 AWD.

Vehicle started leaking antifreeze over the winter. Not bad but had to top it off every month or so. Consumption has slowly gotten worse, then recently I stated getting a sever miss.

I was getting 3 codes
Random Misfire
Cyl 4 Misfire.
Cyl 7 Misfire.

Today I took it to a friends house that has some cooler tools than I do and checked the cooling system for exhaust gasses. There were no exhaust gasses in the coolant, and also the oil level has not risen or turned to mayo.

I figure head gasket is definitely not the problem, especially since cyl 4 & 7 are on opposite sides of the engine, but I still wanted to rule it out and stop worrying about the coolant consumption as a related issue.

I've heard of low fuel pressure causing a multiple misfire condition, so we tested fuel pressure. It's virtually always at 65. If you really rev on it, it will drop just a hair under 60, but the needle barely moves unless you really wind up the engine.

Since cyl 4 & 7 use the same coil pack, we thought maybe it was the coil pack that was bad. We switched the left and right coil packs around, cleared codes and went for a drive. We came back with the same cyl 4/7 & random/multiple that we did before.

What else could cause this? I'm stumped

 

[pbnj22]

I had those same cyl misfire a few months ago... started with 7 then moved to both... replaced spark plugs and plug wires and good to go... you could try moving plug wires around to see if the misfire follows that wire...

 

[FourBinLabs]

I'd say you were right. I changed the plugs after finding # 4 was broken, then I swapped wires # 3 & 4 just to check and it is running just fine now.

Thanks for the suggestion. I feel kind of ridiculous for not checking plugs/wires sooner, but I'm more familiar to my older truck with a distributor. I didn't even consider how something like a short on one plug or wire would affect more than one cylinder in a waste spark system.