1997 Buick Skylark wont start when hot

I am looking for some help. it is my grandma`s car a 1997 buick skylark it will crank and run fine until it gets hot then it will shut off and won't start for like 1-2 hours later i have already replaced the fuel pressure regulator and that didn't help so we then discoverd that the fan wasn't working so we changed that and it came on when we first crancked it up and the second time we did we didn't hear the fan and we tried it today and didnt hear it again and we timed it it ran 17:00 the first time 13:00 the second time and 17:00 the third time and we got a code reader and it says p0300 which in the book that came with it said random/multiple cylinder misfire detected