So, i actually have some questions about 2 different cars, i'll start with the more worrying one:

So, my dad's 1998 ford expedition EB with the 5.4L triton V8 started vibrating at idle and under heavy acceleration, however this was back in february, and we haven't really had a chance or the money to do anything about it either, but we may be able to soon, so i've been researching and from my understanding it can either be from the u-bolt, or it's misfiring, does that sound right based on the info? also, since we've taken so long to be able to fix it (yes we have been driving it in the time since then, at least for trips within our city, as we need our car) how likely is it more parts have been damaged since, and if it's likely enough, what's most likely damaged, and will it even be worth it to fix it at this point? Also, some questions about other non working things if it is still worth it to fix it, first thing, our's has the rear powered quarter windows, however they don't seem to work, we've tried replacing the fuse (as whoever owned this car before us was an IDIOT, had what looked like some sort of speaker wire going around the prongs on the dead fuses to force connect them (not that it worked as far as i can tell, as one of the fuses like that was the one for constant 12V for the stereo head, and it most defintly was not getting the constant 12V until that fuse got replaced)) so i assume it's either something with the wiring, or the motors themselves? also, back to the radio, it didn't have one, so we bought our own stereo and attempted to install ourselves, however the speakers don't seem to work, and there are 2 sets of speaker wires, according to multiple guides i found online, one set is the set going to the amp, and the other are the ones that are supposed to go from the AMP to the speakers, tried wiring to both, no sound either way, again i assume that it's either the wiring, or the speakers themselves being fried.

now for the second car, my mom's 2005 Nissan Armada SE that she just got MAYBE a month ago has an issue where if she goes on a long trip, then after a while of sitting starts the car, white smoke will come out of the exhaust, which according to my research was a common problem, and is almost always the valve covers, and pvc pipes and all that, which is a little out of my range of mechanical expertise, so my mom took it to our local nissan dealer and had them check it out, the cover was fine, however some of the pvc or pcv pipes or whatever it is were leaking, so they replaced that, we recently had gone on a trip to vacaville which is about 2 hours away, when we got going to get back home, it still smoked on startup after (i'd say it was left to rest about 2 hours maybe) and when we were back at our city, it was even smoking just running, and every time we came to a stop light you'd see it, so since it's not anything to do with the valve covers and pvc pipes and such (as again everything that was leaking to do with that was fixed) what else could it be causing that?

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Me, I'd ditch the expedition, they tend to become money pits when that old. s for the nissan, internal engine wear does that a lot on those. Do a wet and dry compression test of the engine, to see if it's worn piston rings, where the pressure would increase on a wet test, or worn valve seals which would not effect the test pressures