The fuse just keeps blowing and the truck just dies. I dont know what the problem is. sometimes it will run for a while on a new fuse, sometimes it blows the fuse immediately. Seems to blow constantly now.

check for incorrect bulb in use at the rear
check for short in bulb socket holder

The 10amp ECM fuse powers all of the sensors controlled by the computer.
You may have to get a shop manual to get the diagrams to check the circuits. You might check to see what is off when the fuse is blown to verify it involves the computer. If the TPS is shorted to ground it would blow that fuse.

Using a smaller fuse should make the problem happen more often.
A mechanic would unplug the pump harness at the tank and check the circuit for high resistance or a short to ground.
If nothing is found in the harness, I would suspect the pump in the tank.

you have some componet that has melted down contacts (it's hotwire is grounded) so every-time u turn on the key power is fed to direct short and the fuse blows.So look around at things that dont work.after fuse blows does motor still operate,keep it running and find out what doesnt work then check that component for melted,grounded wires...

weneed to find the open line of your electrical wiring

Is it the ecm fuse. Check the o2 sensor wires. On this model sometimes they rub on the rear driveshaft and blow fuses.

Are you using the same power feed from the old radio? If so, your new radio may require a higher current fuse. Check the manufacturers information the came with the custom radio and make certain the current (amps) required is the same.
If the new radio has a higher power amplifier for increased audio, it will blow a low rated fuse.
On the other hand, it sounds as though you may have pinched the power feed wire in the radio bracket, trim cover or have it resting agaist a sharp bracket. So when you put the car in drive, the dash flexes enough to cause the short.
Does it blow the fuse when you shift to reverse?
let me know.
Regards,

you may need a new battery now that your altenator went, try jumping your car dose this help ?
with wireing problems like this you may need to find a trust auto shop.

you have a short on black and white wire coming from the atlternator to the inside fuse box trace the wire and you will find your problem i am send you the wire diagram in the next few minutes to help.

Check your ignition/fuel pump relay---it's with all the other relays in a dash tray---it's ORANGE---check it for dead-short.