Hey im new to the forum's and im hoping i can get some help.

My dad recently bought a 1997 f150 with a 4.6l for a work truck.

The truck had been sitting for about 3 years because the man that bought it died and his wife had it sitting at thier house and did not drive it.

When we went to drive the truck it would'nt start because over 3 years of gas marinating the fuel pump died. So we replaced the fuel pump, changed the fuel filter, and the truck started up but ran horribly, and was detonating like crazy the whole way back to our house. We filled it up with gas and then replaced the spark plugs and added some fuel additives in an attempt to clear out the system. The truck has slowly improved, but it still skip's at idle, and runs rough in general. The firing order is correct, and all spark plugs seem to be getting spark. Cylinders 2 and 3 seem to not be doing much when u take spark or fuel away from them it runs the same. I swapped around all the fuel injectors and it ran the same.

If you could help point me in the right direction i'd love the help.

Thanks -dan

 

With cylinder 3 involved, I would check the EGR valve.