Fuel Hoses Lines/piping And Fittings problems of the 1999 Volvo V70

Car repeatedly stalls with no explanation. Volvo dealership has worked on car 8 times. Throttle parts have been replaced, etm, and many other parts. Now they say it's the catalytic converter. This is extremely frustrating and scary. There seems to be no rhyme or reason to why the car stalls. Sometimes, it will act as if there's a clogged fuel line, then it stalls the next time I have to decelerate. Other times, it dies when I'm driving.

Turbo return lines are leaking - rubber hoses are stiffening from heat - shouldn't these have been metal lines to begin with. This is a pollution and fire hazard.