When driving this unit around it will all of the sudden rev the engine up a little bit and then the engine quits. Will start right back up and might do it again 15 times in a row or wont do it again for a couple hours. I have only had it shut off on me once and all the other times it was on the operator. So every time the operator calls me to look at it, it works fine. Checked all the connections on the sensors on the throttle body. Didn't see any rubbed through or corroded. We actually have 2 combi units that do this same problem. Really intermittent. Sometimes go away for months. Any help is appreciated. Thanks

Here is the model and serial of both units.
CL70055LA00 serial 8614
CL20100LA47 serial 7982