1985 Deville

I have a 85 deville that only has 35k miles. It is in excellent condition, but has a couple problems we can not seem to fix. It dies when slowing down. You stop and starts right up. We flushed out the gas tank and changed the fuel filter and pump, but it still dies. We do not know where to go from here. It also over heats and the overflow dumps out coolant. It doesn't happen everytime, just once and awhile. STUPMED! NEED SOME ADVICE.