Engine shuts off bogs down while on highway and stalls?

I had a similar problem with 2 Chevy trucks. One was a 96 1/2 ton with 350. A single wire from the coil became frayed, and when I took a turn or hit a bump or something similar, the engine would just die. I could restart it, but it was annoying as hell. The other was an 01 3/4 ton with the 8.1L v8. After a rain, the engine would just stall after about 5 miles. Dealer said it was the fuel pump. WRONG. Drove it out in the rain, engine died after 10 miles.
Took it back, told the dealer to DIG IN to that COMPUTER, and find the trouble codes (even with NO CHECK ENGINE LIGHT). They found it, and could even tell me how many miles since it happened on multiple occassions. WHY DIDN'T THEY DO THAT THE FIRST TIME! Problem - bad crank trigger sensor, an 8 inch rod bolted to the frame, with the sensor right next to the harmonic balancer. The rubber casing on the sensor rod was completely cracked, allowing water to get in there and causing the crank trigger sensor to fail. Would they give me a refund on the $1000 repair to replace a fuel pump that I didn't need? NOPE. Last time I took a vehicle to THAT GM Dealership.