2001 GMC Jimmy Jimmy Diamond edition

I have a 2001 GMC Jimmy Diamond edition with only 26k miles on the clock I have owned the car since it was brand new. I hardly dorve the vehicle but am starting to use it alot now.

Recently I began to have an issue with the vehicle stalling out and running rough. Upon inspection I found that the truck all of a sudden had two dead cylinders.

first I changed all the pluges, wires, fuel filter and air cleaner. All of which did not help. I was told the fuel injector spider could be the cause and after taking it apart we found the distributor had play in it. So of course I replaced both and the truck ran fantastic for a few days.

After a few days one morning I started the truck up and it ran a little rough the service engine soon light came on but the then the truck ran perfect. 3 days later the light goes off and stays off for almost a month. Now it has been coming on and going once a week. I put the vehicle on the sanner a few times and was getting either a P0305 or P0300.

At this point I am not sure what would be the next steps to trouble shooting this problem and was hoping someone here could help.

Thanks
Tom