COHF13

ok... i bought this ford lariat 5.4 about six months ago, this truck had this grinding noise which resulted to be the trans... which is fixed already. But it also stalls when i press the accelerator continuously, for example when driving in traffic where i have accelerate frequently. Also when i press the accelerator it takes about from 2 to 3 seconds to respond. when i let the accelerator go the engine rpms decrease very low or the engine stalls. I already replaced the fuel filter, air filter, added fuel injector cleaner, i replaced the tranny gears, and replaced battery.

FYI the engine light DOES NOT turn on at all. Also the previous owner gave the truck HELL and had a sound system on it which i think the battery didnt work.

ps.... truck has 136000 miles

DoubleVisioN

Well I'm not here to steal your thread by any means but I thought itd be useless to post another thread If I'm having the same problem .

My 04 5.4 (not a lariat) does this as well. I live on an airforce base and the speed limit is 30 so sometimes I set my cruise control to 30 and it will kill the engine . When I'm driving and coming to A stop such as a red light it will sometimes stall or try to (lights dim, air conditioner stutters.) I have also had it stall being in a drive through in park . I went to reach in the back seat for something and my foot touched to gas pedal just enough to raise the rpm's about a hundred but not enough to make any noise (If that makes any sense) and my rpms lowered and the truck died . When it dies there is still power but of course the engine is not running. My truck has 88k miles on it. Bought it at 86k so this is kind of frustrating.

DanKam81

i had the same problem with my 05. replaced the cam phasers and it went away. was told that there was not enough oil or oil pressure getting to the motor and it would shut down at low rpm because of this. ive owned my truck from day one and it has been nothing but a nightmare.

Grrrowler

My '05 5.4L did the exact same thing as yours Doublevision. I found some info online that indicated that the throttle body position sensor could be faulty. Apparently the 5.4L engines through 2005 had this as a recurring problem. When mine finally threw up a check engine light before I could replace it I had the dealer look at it and the code pointed to the throttle body (big surprise). They replaced the entire assembly and the problem hasn't come back since. I also got slightly better mileage after the replacement.

The sensor alone is about $75 and you can replace it yourself in less than an hour.

DoubleVisioN

Thanks grrrowler ! Ill go ahead and try that ! I was preparing myself for bad news but that's not even bad ha ha .

DoubleVisioN

Thanks grrrowler ! Ill go ahead and try that ! I was preparing myself for bad news but that's not even bad ha ha .

blayne

Before you try anything too expensive, spend $7 on a can of MAF / Electrical component cleaner and clean the mass airflow sensor. I posted more about it in the original thread, but I had a similar problem with the engine wanting to stall when really "on it" and after changing the fuel filter, cleaning the MAF sensor did the trick.

COHF13

Well.... I took the truck to a local mechanic, He changed the spark plugs (6 of them broke =/) and replaced the MAF sensor and nothing.... truck seems to be worst now... I am not sure of replacing the throttle body position senor or just taking it the dealer? What do yall think?

Ruprecht

I'd definitely find a new mechanic if the last one broke 6 plugs. The MAF probably just needed cleaning, not replacing. Sounds like TBPS is the next thing to address. You can do it yourself, or let a competent mechanic do it. Not the other guy, lest he break the sensor off too, haha.

04BigRed

I was having the exact same problem on my 04 with 5.4. Last week I took it to the mechanic and turned out to be that the throttle body was all gunked up. Cleaned everything up and is running much better. Just my experience, hope it helps.