1997 Chevy 5.0 Strange Electrical Stuff

Hello All,
This is a long one but please bear with me, it gets good at the end. My 1997 2500 Pickup w/5.0 has had an intermittant starting problem that I have lived with for about 1 1/2 years after spending over $1800.00 with a professional parts replacement technician. The check engine light has always been on , and the problem is that the engine cranks fine but doesn't usaually start until the third try. Sometimes on the first attempt, never on the second, and almost always by the third unless it has been a damp rainy night. It has always eventually started so I have just lived with it, suspecting something to do with the fuel injectors, as when it does finally start on the third try, it is with a large high rpm surge that quickly settles down to about 900 rpm. The engine runs strong and gets about 18-20 mpg. Other than occasionally blowing fuse #9 (I think) for the dash lights and tail lights, life this way was fine until the other night on a 45 min drive home. I first noticed that my dash lights were out as I got off the highway with about a ten minute ride left. Pulling onto a residential road the transmission shifted with a hard bang that could be repeated, and all dash warning lights went nuts including my speedometer pulsating with the blinker flashing. I made it home as a buzzing a whirring noise was coming from under the dash from my brake pedal. As I pressed the pedal the noise changed in pitch then the engine died and could not be restarted. I replaced the alternator and the battery. I then noticed for a few days, it repeatedly started on the first try and the check engine light was out. It ran fine on a 4 hour drive to Maine (third try start, check engine light on). On my return home, it started on the first try and ran for 30 minutes before stopping for gas. Restarting at the gas station, it ran for 10 seconds the died, and I mean dead. The key chime was gone, no cranking no nothing. As I pushed it off to the side I heard the noise at the brake pedal again, and when I touched it it stopped. I put a voltmeter on the battery and it showed 12.6 volts but all was dead. I pulled and replaced all relays and checked all underhood fuses, and put in the key, got the chime and started up with a low idle that I had to nurse at first, no check engine light, the clock had reset to 12:00, and drove 3 1/2 hours problem free. I have since started a number of times 1st and 3rd try with and without check engine light and once running is ok. I have noticed that sometimes it settles its idle at 900rpm and other times it drops from 900 to 800 to 600 then to 400 where I have to nurse it and then its ok. Today I heard the brake pedal noise for about three seconds just after starting and taking off, and the truck stalled and died as before. Completely dead other than still making the buzzing noise and a strange noise with the key in. After trying the relays again with no success this time, I disconnected and reconnected the battery cables and it started right up with a very low about to stall idle. I got onto the road and it ran perfectly and again the clock had reset to 12:00 . Thanks for reading it through! Any ideas?

so much info...whew... i guess i would start by seeing if you get power to items like the lights when all seems dead.. if so i guess i would replace the ignition switch. that is up there in the area of the brake pedal and might be causing the noise you are hearing.

Thanks for the reply Chris. When it dies everything is dead. I'm looking into a possible problem with the battery. I installed one of the new EXIDE orbital batteries when the alternator went as my old battery was 5 yrs old. The new one has hookups for both side terminal and top posts.

check the connections at the starter