answer for thekidd...
My '91 had a K&N drop in filter, dual exhaust with Turbo mufflers and Borla intercooled tips, billet grille, eagle rims, BFG radial t/a tires, and a $3000+ stereo.
As far as how long it will last, that depends. If the oil was changed every 3000 or 5000 at the most, and all the fluids were changed every 30,000, it should last a good long while. When I sold mine, which was about 3 or 4 months ago, it had 160,000 miles on it, and the engine was still running just fine, but the tranny was what was giving me troubles. I had it rebuilt the first time right around 140,000 or so, and I think the shop that rebuilt it did a half a$$ed job, because less than a year later, I lost 4th gear completely... yeah that sucks alright. So I took it to a different place (it was origianally rebuilt at a place in Mississippi where I used to live, but now I live in Indiana) and they fixed that problem, so then it had 4th gear, but the tranny as a whole just sucked. I mean maybe it was working the way it was "supposed" to, but I just didn't like it, I never liked that tranny. Also I used Mobil 1 synthetic on my 91 ($5 a bottle is flat out a waste of money) and also that Engine Restore Lubricant. I would have to say that I recommend that stuff. It costs around $10 I think, but I really think its good on older engines.
If you're planning on putting a lot of money into your '91, I'd think twice about it. Now I know, I was in your place before and no matter what I say you'll probably spend a ton of money on it anyway, but let me tell you I've been down that road before. Like I said, I put $3000, yes, a 3 with three zeros, into the friggin stereo. Thats ridiculous. Its even more ridiculous to put much money into performance related parts for the most part, because I don't care if you change your oil every 5 miles, its not gonna last forever.
My advice is go ahead with either a KKM or K&N, and a reasonably priced exhaust system, I think I spent right around $225 for mine. Thats all I'd do to it. Then save your money and one day sell your 91 and get a newer Explorer with a 5.0L V8....... man....... its SOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO much different than driving my old 4.0L OHV....... man.......... If you like your current Explorer and you are wanting power, you'll love a v8.
Or if you are either mechanically inclined or know someone who is, you could drop a 5.0L into your Explorer. I thought about doing that to mine, but for one I work at a Ford dealership so I get great deals on cars, plus I found a perfect 2000 Limited 5.0L that I just loved. Also putting a 5.0L in an early model Explorer isn't a light task.
In my opinion, a suspension lift is a big waste of money. If you want bigger tires, I can understand (again I wouldn't put too much money into it) but I'd get a body lift because they're MUCH cheaper, and very easy to install.
I know you'll do what you want, and I guess you should, but thats just my advice. Take it for what its worth.
