I have a 7 that dies @ 4500 rpms. The new Snap On Scanner say that the thermo sensor will cause this. I have looked in manuals and diagrams and don't know what to look for. have found parts called water temp sender and water temp sensor. I have found listing for water thermal switch. My temp guage is working. When rpms get below approx 4500 engine picks up and runs fine. Any ideas?

 

I don't know RX 7s specifically but I'd be very suspicious of a fuel filter/supply problem with RPM and or hard throttle problems. If you haven't changed the filter in the last couple of years I'd just go ahead and try that first -- it is a routine maintenance item anyway.