Help,
I've been going around in circles on this one. The original scan gave me a code 161 and 300. so I changed the Oxygen sensor. Now I get code 300, so I changed the fuel filter, and the spark plugs. I still get code 300, Random misfire. When the truck is going uphill at about 110km, the check engine light flashes. When the truck isn't working hard, the check engine light goes off. The Truck now has 130,000 km. Any help to diagnose the problem as opposed to just changing parts would be appreciated