HELP cylinder 4 and 6 misfire

[Fox Ridge Ranger]

i have a 97 4.0 ohv 4x4 ranger. recently it started misfiring on 4 and 6. it idles rough, studders and shakes very bad under acceleration.

brand new coil pack. brand new sparkplug wires also. the plugs only have 2000 on them. recently upper intake manifold gaskets were replaced. cleaned MAF. Ran seafoam. i had a shop run a scan on it and all that it was showing was the 4 and 6 misfire.

It seems to go through coolant. sometimes it leaks externally and other times it wont... blown head gasket? faulty injectors maybe? cant think of anything else help or similar experiences please.

btw new to forum! Hey to all
heard this was a great forum and had to join!

 

[Tbars4]

..Was it misfiring before the new coil pack and have you ruled out wires, plugs, and injectors?

 

[tmwalsh]

If you are absolutely sure it is two cylinders misfiring, and they are not adjacent to each other, then I'd do a compression check on all 3 on that side.
Pull and inspect the spark plugs looking to see if they have been 'washed' by coolant. If you have been 'burning' coolant, you will soon get to replace your catalytic converters, from what I've read.
You can also check for a leaking intake by using a propane torch with a hose attached to feed a 'whiff' of propane all around the gasket areas of the intake with the engine at idle. Supposedly the engine will smooth out if it gets propane added to the mix via a leak in the intake.
It would not hurt to check the fuel pressure. Does this engine have the internal EGR ports in the 'floor' of the intake manifold? I've heard of some {3.8 mostly..} that will get one port that is not plugged, and all the EGR flows through that port, overwhelming that cylinder with EGR gas. If you have floor ports, try blocking the EGR flow for testing purposes.
tom

 

[patch1010]

When mine did that, I had a cracked head. Checked both of them, one was real bad the other starting to get bad. Replaced both heads with aftermarket ones. If that is the problem, check for the port sizes you want. Intake and exhaust. Boise block and head did my head work, Buss automotive did the R&R. My mpg went up about 2mpg. I now average 20-22 mpg normal driving, with almost 24 on the freeway if I keep rpm 2500 or below.