Cant really run both. A diesel runs on diesel fuel and is complemented with propane. The propane allows a 100% burn of the diesel fuel thats why it makes more power.

 

I don't know if anyone is still reading this, but there are many options that you can use on your ford. I would recommend using autogas. It is one of the best products for your motor. It is easy to use and the software is very helpful. I have a product called versus. It is ok, harder to tune. This is CNG not propane. A tip for anyone looking to put this on your truck, make sure all spark plugs are replace and o2 sensors checked as well as coil packs and emissions. This will help with the tuning. Also if you don't do it your self make sure you have someone that knows what the are doing, especially with the 5.4. I hope this helps anyone

 

Something to think about...

Non-CNG heads will work for a while but after so long, running CNG on them will begin eating away valves, guides and seats. "Flex Fuel" engines that are in later model trucks have harder seats and different material guides and valves installed.

Just food for thought.