94 Exp. 4.0 lack of power etc

94 with 220,000. Started stuttering at idle and under load. Codes came up for maf, and ect sensor, both replaced, still stutters. Surges at highway speed and at idle you can hear it sputter near the tail pipe but it sounds and looks smooth at engine. New muffler, cat, maf, ect sensor, plugs and wires about 20,000 miles ago. It's about to baffle me. Any help would be appreciated.

Have you checked all the vacuum lines? Also, make sure the air intake hose between the air filter and throttle body is installed properly (no rolled lips at seams) and is tight.

If you have a vacuum leak or unmetered air entering the intake, you could experience the symptoms you describe.

-Rod

Ran several vacum tests, all which appear to be normal. Starting to think maybe a valve or head gasket. Never dealt with valves but have more than a few head gaskets under my belt and it's showing no other signs of head gasket issues.
Thanks for the reply.

Before pulling the heads for a valve job, I'd suggest you perform a compression check on all 6 cylinders.

Also, you may want to pull the EGR valve and clean it. Use a vacuum pump to make sure the EGR valve diaphragm is still good.

-Rod

Could a bad injector be causing it? Brainstorming here trying to come up with ways to fix it that do not include major invasive surgery. Ran compression check and all six came out within 10 pounds of new. The plugs however were pretty dirty. (Bosch plat +4, replaced with motocraft - back to factory).

I suppose a bad injector could be causing it, but I wouldn't necessarily start there. It wouldn't hurt to try adding a bottle of fuel injector cleaner to the fuel tank though. I've experienced injector cleaner correcting some pretty extreme driveability issues.

Another chemical you want want to try is SeaFoam. Read the can and use it as a cylinder de-carbonizer. Carbon build-up on the valves or piston could cause what you describe as well, and potentially still allow the compression to be within range.

-Rod

I suppose a bad injector could be causing it, but I wouldn't necessarily start there. It wouldn't hurt to try adding a bottle of fuel injector cleaner to the fuel tank though. I've experienced injector cleaner correcting some pretty extreme driveability issues.

Another chemical you want want to try is SeaFoam. Read the can and use it as a cylinder de-carbonizer. Carbon build-up on the valves or piston could cause what you describe as well, and potentially still allow the compression to be within range.

-Rod

I use sea foam in the fuel from time to time but never have tried to de-carbonize with it. Good idea. I will give it a try. I ran a botlle of injector cleaner (3m) and that has seemed to clean it up some. Thanks again. I will post more results.