bigbluefan09

Hi all new member here. I have a 2003 F-150 with the 4.6. Love the truck but the engine seems very sluggish. The truck only has 76,000 miles on it. I pull a small boat and as soon as hits any kind of incline the mph drop and down shifts. The is a very small boat not heavy at all. The truck even does this without a load on it. I have tried brake torque it but won't brake the tires loose. I need some help on finding out what the problem could be. No engine lights on or anything. Hope to hear from you. Thanks, Aaron

02flaresidesport

Have you tuned it up? air filter or fuel filter maybe?

bigbluefan09

It has a new air filter, haven't had a chance to change out the fuel filter yet. It is just strange how it looses so much power as soon as hits some kind of hill. Once it downshifts the power is there but it shouldn't be like that

02flaresidesport

Yeah there is definitly something going on. My buddies 97 4.6 truck has 156k and still pulls very hard and strong.

rompn4x

my 4.6 with 163k on it will fry the tires ( I try not to beat on it) lol

Fishingnbeer84

throw in the mods,stocked tuned 4.6 sucks ***. I know from experience. Takes like 2 mins to accelerate to 60. lol. Try cold air induction,ehaust,and- or programmer/tuner.More air and fuel makes alot of difference.

4.2to5.4

those are tipical symptoms of a fuel filter problem try replacing the extiror filter if that doesnt work replace the fuel tank sock also maybe an injector service

bigbluefan09

I changed the fuel filter today and it didnt seem to do much at all. The filter was pretty nasty but i still cant get the tires to brake loose and still no power up the hills. I also put a bottle of fuel injector cleaner in it but that seemed to make it run worse. Running out of ideas here. If anyone else has any ideas pls let me know. Thanks again

40thmustanggt

try changing your plugs you say there's no light on? change your plugs clean your IAC & Maf sensor. then run a 1/4 can of seafoam through your vacuum line run the seafoam before you change your plugs, how often do you get on your truck? sounds like alot of carbon build up if none of that helps let us know.

40thmustanggt

also you say it does fine once it shifts down. how does your transmission shift? does it slip any? when you try to power brake does the rpms come up and bog? give us alittle more info.