1995 Chevy Blazer P1133 Heated Oxygen Sensor (HO2S) insuffi

Iok when I bought the truck from my uncle he said the truck sat for about three months so I gave it a tune up I changed the plugs, wires, car, rotor and air filter also the pcv valve I bought a fuel filter but I cannot break loose the fittings so I decided not to change the fueil filter. The reason for replacing all these parts is because the check engine light came on so I took the truck to the nearest auto parts store for a obd2 scan to see what the problem was I had the folllowing codes show up p0141, p0172, p0300, p1496 after the tune up I got rid of 3 of the 4 the only one left was the p0300. The check engine light never went off.

So I kept on driving the truck I had no choice I recelntly took the truck get another scan because I could smell how rich the truck was running and the check engine light would blink if I sat too and the trick would start idling rough I had two codes come up p0300 the random multiple misfire and the p1133 manufacturing control fuel and air metering.

Someone please help and explain how to get rid of these codes.