Fuel pressure regulator might be clogged full of crap too. It acts like a third state fuel filter and sits atop the fuel pump. It wouldn't hurt to change it.

 

the M1 intke will give you better performance and yes it will eliminate plenum...but the cheaper way is to kegger mod, and hughes plate

 

even cheaper method to use that some have had luck with is the newer shorter plenum bolts that dont bottom out before appying enough pressure to sandwich the gasket properly and hold it in place.(old factory ones were too long and this was acknowledged by Dodge)...just throwing that out there. you can do the hughes if you really want to be safe.. (search for and read that thread titled "plenum")

 

Ok, I have thought about it, and I have decided to go with a M1 intake. I don't really care if I lose a little low end. I don't ever want to worry about the plenum again. It is just another potential point of failure. I plan on running this truck into the ground, so it just makes more sense to get rid of the plenum all together.

 

IMO thats a wise choice

 

I get 10mpg in my white truck. its a 5.2 longbed, all stock. 87 octain. so 10 with a 5.9 is definatly spot on.

 

Not really....there are lots of factors that change this from gears to tire size to weight of truck (reg cab vs club)....I get about 12 mpg with 35" tires and 4.56 gears on my 5.9 (140k) and thats pretty bad actually....I dont burn oil or anything but imagine somethings not quite right like the plenum or maybe deathflash...drove my dads 5.4 f150 today....waaaaay more power than mine....sigh

 

ok first of all its a dodge, if you want more mpg i suggest a Chevy.

2nd its a dodge plugs have to be changed around 50,000 wires dont have to but it a good idea

3rd if a dodge house put a plenum in it they prolly put a steal one back there for problem comes back just this time no warranty

 

the standard copper plugs most use here should be changed way before 50,000 miles...along with the rotor and cap... and the average highway mpg for the 5.9 was 16-18 mpg and city was closer to 11 so yeah there's likely something wrong. Even if it is just your driving style...some like to get from 0 to speed fast that waste lots of gas as well as waiting till the last minute to break....I changed my driving habits on my vette once and the mpg computer told me it went up 4mpg on average...
and the new Dodges get pretty good mpg actually, so...

 

i stopped using standard copper plugs when i only got 15,000 out of em. now i run bosh platinum 4s and im gonna change them at 50,000