I have a 2006 Tahoe 4WD 5.3V8 with 170k miles on it. New transmission at 110k. It has been a great vehicle, but a couple of years ago it developed an issue where it would die when I hit a hard bump. It did this for quite a while but I was able to live with it since it only happened on off road conditions. As time went on, however it got worse until it would die even hitting seams in bridges. It just dies but you don't even notice until you hit the gas and nothing happens. No dash lights, no indication. Just going down the freeway at 75, cross a bridge and the engine isn't running anymore. Put it in neutral, crank it and it starts right back up on the fly, back into drive and I keep going! Needless to say my wife does not appreciate this feature! It also developed a condition that it almost always takes two attempts to start. It used to start immediately when you turn the key, but now it will crank and then stop, and then start immediately when I turn the key again. So I broke down and dug into it. It never lit the check engine light, but it did generate codes for camshaft sensor signal high and low P0342,343 (which is contradictory). I checked all of the wiring possible. Added additional ground wires between the engine, battery and frame. Did everything I could find online as a possible remedy. I replaced the camshaft sensor and checked all the wiring to it. No change. ($60) I had the fuel pump replaced, no change ($200) Took it the dealer, they put it on their computer and drove it for two days and then gave it back and said it was misbehaving but they could not find anything wrong ($100 later). I called a local mechanic who claims to be the Chevy expert and he said I already did everything he would try, so I should put on a helmet and crash it into a wall and collect the insurance, but otherwise had no suggestions. As a last hope I replaced the camshaft sensor and the ECM. ($200) This stopped it from dying under normal driving conditions, but it still dies on really rough roads. It still sometimes stumbles when I hit a bump like a bridge seam and the tach briefly drops near zero and then pops right back up, but it does not die (yet). It also still takes two tries to start. So I'm just fishing for anyone who has experience or suggestions before I take the mechanics advise or trade it in for something that works. It's a great vehicle and I'd hate to give up on it, but it's not reliable and I can't trust it so something has to give. Thanks!