stalling at 70mph on highway

I have a 2000 Alero gl 2.4l engine and about 6 months ago i was driving on the highway and my car stalled out at like 70. I shut the car off and then turned it back on and it started back up. On my way home that night it did this about 5 times and then it never did it again. Well last night i was on the highway and it did it stalled out again at about 70mph but this time it wouldn't start and it still hasen't started. It will start and sometimes it turnsover for a second but then stalls out. My dad and brother our both mechanics and a few educated guess's about what is wrong but before i go crazy and fix things and find out they our not the problems i am asking for advice. Could it be fuel filter, water in gas i live in Northeastern Ct and it has been really cold at night and my car is outside, altenrator, fuel filter or pump any advice would be a great help. Joe

Spray carb cleaner or starting fuuid into the intake see if it runs then you know it is a fuel delivery problem if not start by checking for spark, this is basic diagnostics.

Spray carb cleaner or starting fuuid into the intake see if it runs then you know it is a fuel delivery problem if not start by checking for spark, this is basic diagnostics.

Hello thank you for your advice. I changed the fuel filter and after toying with it for a bit it ran again. Do you think the reason the car shut off was because of a bad fuel filter. My dad and brother think the alternator is bad but it is currently putting out 15 volts but it sounds like it is making a loud scratchy pingy noise that comes and goes could this be the alternator. Joe