You need a coolant pressure tester, it hooks up to the cooling system (rad cap or tank) and it pumps up pressure in the cooling system (engine off and cool), Pump up to 10 lbs and see if it holds, if not there is a leak, could be intake gasket, head gasket, or other leaks, and you can also watch the pressure build while the engine warms up, If it builds up fast and high (15+ psi) cylinder is pressurizing the cooling system, bad head gasket for sure.
And garbage plugs are not uncommon - I have tried the cheap route (autolite, etc.) and ended up going back to Motorcraft. Another thing to check is WHERE the noise is coming from, mechanic stethoscope or plastic tube, place it on different spots to try to see where the noise is.

 

I'm confused - Nuff said.

 

do you think that equipment to do the test is rentable at autozone or something? Is it possible that this problem is causing the rough ideling?

 

I realize that. sorry. my brain is fried i have been working on this truck for 15 hours. the truck that is giving me all this trouble is a 200 Ford Explorer with a 4.0 V6. its My wife's aunts truck. so if i dont get it fixed i'm screwed. you knbow how inlaws are.
My truck is a BeastMode F-150 Supercrew. i have done alot to my truck, cold air intake from airraid that i ducted fresh air to from behind the head lap, throttle body spacer, super coils, full exhaust kit, and superchiped it.

 

I couldn't tell you much about DOHC engine. You might try the ranger forum if you can't get suggestions here.

 

The MAF sensor was dirty so I cleaned it with throttle body cleaner and ta-da problem solved