I bought this 94 explroer 4wd for cheap

It have 150K miles. It run so rich it pour black smoke. Bad ball joints.

Now I replace MAF sensor that actually stop run rich and black smoke. One problem. My friend can smell gas out exhaust. He say very stink. Owner run this rich for few weeks so I think cat converter is plugged? It heat on frame and transmission to HOT.

I run sea foam to clean carbon so that affect spark plug look white?

Interested later until now.
I have misfire on #4 cylinder. I remove spark plug they look ok it just white. It was Autolite. Look to be 1000 miles on it. It stop misfire.

Now it run fine then again #6 cylinder. I remove spark plug they look fine it just white. It still have misfire. I put die electric grease it still misfire. I unplug on coil pack it have spark.
It misfire when idle but it go away when rpm are up.

Fix EGR valve with punch/ hammer it was sticky.

Temperature gauge alway stay cold but very rare it go to middle if drive HARDER. It pretty HOT. But it still go back cold. I touch radiator hose it very HOT so it work fine.

I remove radiator cap. I see grey gunk on cap. It wasn't there when I bought. Guy only put 2k miles since February. It not foam. It more like grey antisezied. I email owner to ask if he or his sister put bar stop leaky in radiator.

Do you think grey sludge affect coolant sensor to read cold?

 

Sorry for long post.

I never lose coolant and oil still look good no milky.

Transmission oil look light brown do you think that coolant?