99 isuzu trooper loses power when idling or when stepping on gas

What is your question?

I was past down my grandfathers 99 isuzu trooper with 87,000 miles on it but im not sure what is wrong with and it been sitting for at least 2 to 3 yrs and wantedto know if it is worth fixing or getting rid of it... i brought an obd ii scanner from autozone and got a error code p0300 i looked it up and it was a random/multiple cylinder misfire... trooper loses alot of power when stepping on gas or in gear... when the car warms up it seems like to starts to sputter then shuts off and when i try to restart it i cant and have to wait at least 10 to 15 mins