You're exactly where I was this past December with my 2002 Itasca Suncruiser 35U. Previously I'd owned two TT preceded years ago by a self-converted Ford Econoline van and two VW Westfalia poptop campers.
Your TT skills will serve you well since your motorhome's "house" systems are pretty much the same. Here's a link to the 1988 operator manual:
and the parts catalog: http://catalog.winnebagoind.com/menu/Parts.htm
Unfortunately some of the other Winnebago resources (wiring, plumbing, etc.) don't go back as far as 1988 but you may find some of the 1990 resources helpful. Just look under the Resources tab at https://winnebagoind.com/
Here's the 1988 brochure: https://winnebagoind.com/resources/b...Itasca-bro.pdf
You should create a signature containing the year and model of your rig and try to mention it in your postings so you can get responses specific to your rig.
Sooner or later, you're going to need new tires if you don't already have them. Check the DOT code on your tires to determine their age. RV tires age out before they wear out. In my case I was told the tires were six years old and the rig had been stored inside, which means the tires were most likely still OK. After I bought it, I checked the DOT code and they were a potentially dangerous 12 years old despite appearing to be in good condition (another $2,000 I hadn't planned on).
Even if you have new or fairly new tires, you'll need to know about proper inflation. There are many opinions on tires and related issues on this and other forums and most are just opinions based on limited personal experience. What I like about this site is it's based on engineering science. It's been created by a retired tire engineer and will give you pretty much all you need to know about tires and proper inflation. At least read it before wading in to the forum postings on the subject:
This is also a pretty good guide:
(note: each manufacturer has it's own inflation tables for all its tire models)
Just remember, the table PSIs are minimums for a given load and the engineer's recommendation is to add 10%. Also, seriously consider a tire pressure monitoring system (TPMS). I'm a bit paranoid about my dually tires since, when I was in college we lost almost everything in a moving van fire (driven by professionals) that had been started by unnoticed tire failure. Besides, I don't have the discipline to check my tire pressures every time I drive the motorhome.
Good luck and I hope you enjoy DIY.