Russell,
Don't shoot yourself in the foot. It's great that you can work as a mechanic and do well at it, but owning a shop is a completely different monster. Have you taken the time to do an actual honest business plan, cash flow estimate, income statement, etc? If you want to have a better chance at business and at getting a loan, you'll need to have these things. I've really looked hard at opening my own shop and unless you intend to either employ 10 mechanics to help pay the bills or work long hours for low pay with only yourself being the mechanic and all the office work, you won't make much money if any. There are tons of costs involved that people don't really think about. 5 months at a mechanic shop won't endear you well to getting a loan to open a mechanic shop either. Are you an ASE certified tech? If not, then there's one other strike against it.
In all, I say keep looking for a better computer job and consolidate your loans. If you really want to have your own shop, start working on a business plan and make sure it will realistically make money otherwise you'll get even further in debt.
Last, but not least, DO NOT go into business with your buddy, especially if his credit is worse than yours. If you really want to work with him, you own the business and hire him as an employee. You don't want to get roped in with someone else who can't make their own bills in a business as you'll end up owing for their portion of the bills as well.
Rick