P0300, P0131, P0101 codes 99 montana

I have a 99 pontiac montana van.
I had issues with it and got codes for the camshaft position sensor. I replaced the sensor drove the vehicle for about 20 miles and got random misfire codes. Used lucas fuel additive everything was fine.
I moved from Maine to florida recently and these issues are starting up here. WOndering if there is a difference in gas additives here? Been trying different types of gas and grades. It has been doing fine till last night now I have these codes. Would this all be caused due to the fuel down here? I am going to try lucas again and clear the codes. Just mainly curious if it would have something to do with the fuel?

Update, I added lucas to it again and everything is running fine again. Am I just hiding the issues using this stuff?

check the fuel pressure!

Well, P0101 jumps out at me because that's a MAF range code. Usually a plugged exhaust causes this code(but you have misfire codes as well). To determine if it is the MAF or the exhaust, Unplug the MAF and see if the driving conditions improve. If so =MAF. If they don't improve(and I bet they dont) then you'll need to check backpressure in the exhaust for obstructions. This can cause misfire codes as well.