engine dies anytime no accelleration on 1990 Mercury Cougar

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
any time the accellorator is not engaged the car dies, like at corners or stop sign. Also on the dash "SSS" is showing. Is it a fuel issue or engine?
(1) Answer
im guessing it has the digital guages. i can think of a few things.

1)Vacuum leak (probably at the rear of the upper intake, the EGR.)
2)Heads warped or head gasket leak. Yellowish oil would confirm this condition.
3)Problem in the fuel system, possibly a worn fuel pump or faulty pressure regulator.
4)Incorrect timing.

I would expect the head gaskets, i had the same condition with mine, but to be 100% sure if its the head gaskets. you can rent a pressure tester from any auto parts store. I think the pressure should be around 100 psi. if any cylinder is signifigantly lower. this should be your problem