I have a 2004 v6 3.5 terrecan and it is very heavy on fuel. What must I do?

I don't know but if you check the wiring diagram I believe you will find the mass airflow sensor is connected to the engine management computer and derives the power it needs from there; therefore it isn't fused separately and any fuses in the circuit are those providing power to the engine management computer.

Use a scan tool to check the temperature sensor reading,if the computer does not know the engine is cold it will not enrich the mixture for starting.

I recently tried the DIY service and repair manuals from
a website and it actually helped me repair transmission problem in my jcb 3cx site-master. it wont move forward or reverse, engine is good both solenoids for forward and reverse work.
I don't have much technical knowledge but I just followed it step-wise, and works perfect! got it from www.reliable-store.com
All the best

You must remove the fuel tank to replace the fuel pump. This is no fun without a car lift and much heavy equipment is needed and a good amount of car repair knowledge and a full set of hand tools. If you have none or very little of the listed things then leave it to and expert.. DONOT USE ANY TOOLS THAT CAN SPARK.

excessively rich fuel mixture, low tire pressures, excessive speed on highway, open windows at high speed, trunk loaded with lots of heavy junk, clogged air filter, bad wheel bearing(s), slipping transmission, etc.

undo all the fuel lines and vacuum lines, electrical connectors to the fuel tank. undo the fuel filler tube at the tank. support the gas tank as it will be heavy depending on how gas is in it. undo the fuel tank straps and lower the tank. clean the area around the sending unit of dirt and remove the lock ring that holds the sending unit into the tank then you can remove the sending unit to replace the pump. follow the instructions that came with the new pump. don`t use a used pump and change the fuel filter.

clean filters (could be a blockage,also fuel lines etc

plug wires may be worn as well as other ignition parts--the code could mean bad 02 sensors or vacuum leak or dirty fuel injectors--get car scanned by a tech II with a data stream

Mopar 5W-30 is what the book will tell you. Any good name brand 5W-30 will work.

P1664 FIP (Fuel Injection Pump) malfunction (possible air ingress in low pressure fuel side)
Most likey the Diesel fuel injection pump needs to be replaced or overhauled.