66mustang. why is my car dieing. on 1990 Ford Mustang GT

66 mustang 302. car is dieing with no warning after idling for 2 minutes or 10 minutes. sometimes longer and sometimes not so long. it does the same thing when driving it. my temp guage pegs out hot when i turn the ignition to the on position. replaced the temp sending unit. still doing the same thing.

not sure what to try next. any suggestions will be greatly appreciated.

Asked by for the 1990 Ford Mustang GT
The problem described sounds like the chassis is trying to ground though the temperature gauge. I would make sure there is a good ground strap between the engine block and the firewall since the battery is only grounded to the engine block. There needs to be a heavy ground strap between the block and chassis, otherwise the chassis can ground though the transmission and differential arcing gears and bearings.