so whenever i go anywhere, i usually have to give the truck some good gas to get moving. i never really noticed it till i got slightly larger tires.

when coming off the line, if i dont want to get rear ended, i have to give it enough gas to get the rpms to about 1800, then it goes up to about 2200 and shifts back down to about 1600. then repeats this. ive been getting about 400 KMS to a tank. thats 248 miles.

My truck is a 2006 4.0 xlt extended cab with an auto trans and 2WD. my stock tire size was 28's and i went up to 30" BFG At KO. I have 3.55 gears, and limited slip. the air filter was replaced about 6 months back, and is still spotless now. Ive replaced the plugs and wires because i was having a bad missfire problem. (problem was solved)

i was thinking i may have a clogged cat, or a dirty fuel filter. im doing the fuel filter next chance i get, and ill double check the air filter. do my oil changes every 4000 Kms. I havent done a tranny flush or any other fluid flush, though i know i should.

let me know what your next step would be, and ill go through all of them.

i do want to re-gear to 4:10's for a bit more torque in the city, and when if i tow something.

my driving is not agressive and not slow either. i dont let the truck idle for more then 45 seconds. i use regular gas, no additives.

i do in the winter and summer have very short drives. a matter of 8 minutes to work and back.

it also seams i get better mileage when wheeling.

thanks!

oh and im getting 13.05 MPG average. and i do 80% city driving.

 

I don't know if Touque converter is the problem. but there may be one. i would suggest first doing a Tranny flush and a filter change. How many miles/Kms are on your truck?

 

52,000 kms

 

It started with no power at lower rpms and escalated with stumbling on the hwy once the torque converter was locked. When I replaced the coil pack all the problems went away.

 

I dint think that's it, it's got plenty of power if I give it some. I'm thinking possibly in need of a re-gear. The gear ratio was pretty tall even with my small summer tires. I'll probably go for 4:10. I'm at 3.55 now.

 

odds are if it is trans related, the forward clutch is slipping (applied in first gear) but you would get a p0731 code for it.