1999 Toyota 4 Runner Cranks but Won't Start

Hello,
I have a 1999 Toyota 4 Runner V-6 3.4L engine with 211,364 miles. I recently had my truck towed to a dealer because the lower ball joints were worn down and the wheel fell off the axle. After I got the car home, I was unable to start it the next day. The service manager told me that I needed to replace the IAC valve and that the the valves needed cleaning because they had alot of carbon deposit on them. I wanted to know if any of these two things could be causing my problem. Since I can't get the car to start, I can't get it to a mechanic. Also, I was wondering if this was a DIY or better-left-to-a-mechanic problem. I just changed the spark plugs, if that makes any difference. The old plugs had a black sooty deposit on them.