I need some help..... 86 GMC problems!!!

[Kenbo-Slice]

Hey guys. I'm new to this "older" truck world. I don't know about big motors, carburetors and POWER.

So heres to problem.... This truck is a bear to me! I am slowly trying to get this thing reliable (an 86 GMC 3500 dually). The truck has a 454, TH400 and is 2wd. I have recently ran into a problem with the ignition. The truck will start and I'll drive it and when I shut it off it will not start again. I don't mean that it wont fire... It will not do ANYTHING! I'll turn the key and get nothing. No noise no nothing. The clock in my dash is still running so I know I have power. I have no idea what it could be. Any ideas gentlemen (or women)?

Also, The truck was running great all day yesterday until last night. I started it and it was idling so low it would bumble and then stall. I would start it a few more times and it did the same thing. Try it once more it would start and idle fine. Today it was doing the same thing... VERY low idle. I planned on buying a new carb since the local carb shop wanted $225 to rebuild it and i could get a new Quadrajet for about $50 more (then tear apart the one I have and re-build it myself to learn/practice) Does the idle problem sound like a carburetor problem or something else?