2002 CXL Intermittent No Start

I have a 2002 Rendezvous CXL that has an intermittent no start. It will crank, does not set any codes, security light does not come on. I have put a new fuel pump and pressure regulator on it. When it does not start it will fire and run on lubricated starting fluid. I have had it towed to the Buick dealer only to have it start when it got there and they say there is nothing wrong with it. Seems like a problem several people have had. Doesn't seem to be any set time that it needs to sit before it will start again, been anywhere from 10 min to a couple of days. Any ideas on what it might be? We really like the car, and it runs great other than this problem. Would like to get it fixed, gets annoying when it strands you out of town. Any help would be wonderful.

It kind of sounds like it may be an issue with the c-305 connector. On my Pontiac it is located to the rear of drivers seat on the florr, more or less where a rear seat rider would put their feet. There can be water intrusion because of leak or other spill in cabin which can lead to corrosion of wires. I have also heard sometimes the connectors can be spread creating bad connection.