[Eldorado]

first off, this is a period: .
and this is a comma: ,

lol with all kidding aside, both of your cars are just plain 924 models. you dont have an S car. the S was only around in the mid to late 80's (i believe.. someone correct me if i'm wrong).

you could have a problem with the fuel pressure in your 79. it sounds like you're losing pressure in the system and the car dies.. either that or a vacuum leak. but i dont suppose it's a vacuum leak because you say the gas pedal turns to mush... in a vacuum leak, if you pressed the gas, it'd keep the car alive... provided the leak was small enough. a bigger leak wouldn't let the engine run for a minute before dying..

I'd hook up a fuel pressure gauge on your fuel rail and test pressure there...