Why do all my vehicles exterior and interior lights flicker only when the engine is running? Has anyone experienced this difficult problem?

I have a 2004 Ford Ranger XLT FX4 Level II with a manual transmission. Sometimes the flickering lights and engine running rough are worse than other times. They both seem in sync with each other. The truck is now overcharging but I do not think it always overcharged. It is NOT the alternator, plugs that plug into the alternator, battery, grounds, belt, belt tensioner, and idler pulley. Pretty much everything that a mechanic would first check, for example: the obvious things, are all checked and good. I don't know what the problem is. It has to be something causing it.

My 2007 Ford Ranger is tilted towards the passengers side, how to fix?

It's a 2007 Ford ranger v6 3.0L sport 2wd extended cab. Just bought it a few days ago and noticed the entire truck is slightly tilted towards the passengers side. Not really even that noticeable and probably isn't an issue. But it really bothers me for some reason. I've read online it's a common with the rangers but I couldn't find any solutions for it. Is there any video tutorials out there? Maybe a part to install? I would send it to a repair shop but I'm not sure how much something like this would cost.

1991 Ford Ranger heat shield?

My heat shield was removed for other repairs and left off by mechanic. Can someone explain to me, as if I were a child, where it goes and how to put it back on?

Will a catalytic converter for a 6cyl 3.0 work on my 4 cyl 2.3?

I own a 2004 Ford ranger with a 2.3L engine, but I wasn't able to find any catalytic converter for a good price, so I was wondering if a catalytic converter for a 3.0L would work fine on my car, since Catalytic converters for that engine are more widely available, thus cheaper.
Btw I need the rear Catalytic converter, thanks