Ever since I got my truck last year, it's had a weird rapid popping/rattling noise that occurs frequently somewhere in the lower front, but under specific conditions. If I rev up and down in park I don't hear it, but if I'm on the road and accelerate modestly it's noticeable, and goes away some if I accelerate harder or disappears completely if I let off. I'm assuming it's not a bearing or timing chain, since it only does it under load and doesn't sound rhythmic.

I'm thinking maybe a bad catalytic converter? (My mpg seems a bit low and the idle has always been uneven)

I had something similar in my truck that I had for YEARS. A tinny kind of rattle which happened under hard acceleration or on a hill on the highway. Same truck as yours. Here is what I did to finally get rid of it:

1. Followed the decarbon procedure here: The right way to decarbon the OHV 4.0 (Ford TSB) Used PM-3, not Seafoam.

2. Still rattled after the third application so I decided to replace the maf (tried cleaning it with maf cleaner multiple times which did nothing) and the EGR valve (make sure you get the right one for your truck, they can be tricky). It was pretty clogged with carbon and I didnt bother trying to clean it.

3. Put in new spark plugs and wires.

Rattle was FINALLY gone and it feels like driving a new truck.

backfiring out of throttebody?

I had same thing and found out it was carried bearing but it sounded like it was in engine.

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1993 green/gray ranger xlt extra cab eddie bauer leather interior,4.0 17 inch wheels

i also have same truck and noticed that to, havent been able to afford to do all those things yet, but now i am losing power when going up hill at about 40 plus, its weird cause it only happens in 4 or 5 gear most of the time. ocassionally in first after it has sat all day

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94 ford ranger 4.0 5 speed no mods, 2wd