2005 Super Crew 5.4, this is random, but at times when I come to a light the motor stalls. I have to tun the key in the off position to get it to refire and then it may or may not stall again at the next light. On the highway, it seems to run fine. Made trip to Birmingham Saturday about 250 miles (500 round trip) there no problem. Coming home I made quci stop and as I came down the off ramp, it stalled. It will only tirn over and try to start. You have to turn the key in the off posiition then restarts fine. I have read about problems with The throttle position sensor. Since I have to tun the key to the off position, I'm assuming it resets it so it will start.

Truck has 121K, new fuel filter, air filter, plugs changed about 10K ago. No check engine light, but am going to run by and see if there are any codes stored tomorrow on my way home from work.

Today it has been fine. It has done this before, but then went away.

Any help would be appreciated

 

I hope you aren't having injector issues - your extended warranty on those ran out at 120k.

I'd suspect a dirty/sticking electronic throttle. I'd pull the TB and thoroughly clean it.

 

I went and had the codes checked. I had a 316 which he said was a misfire and a 401 he said was a mass air flow sensor. I recnetly cleaned the air flow sensor and I'm not sure about the misfire, unless that is what code is coming up before it stalls.

I am pulling the throttle body off tonight to clean and inspect it.

Any else I should be looking at?

 

If you got a MAF code, be prepared to replace it. Are you running an oiled air filter element (such as a K&N)? If so, I'd go back to a dry element, filter oil is hard on a MAF and it can gum up the TB.

 

I am running the dry filter. Will the air mass sensor cause stalling?

 

It probably could.

 

PO401 is an EGR code for insufficiant flow,not the MAF sensor.

 

Must be a typo - the 5.4 3 valve doesn't have EGR. P0104 is a MAF code.

 

I had the exact same problem .. It was a little plastic elbow on a vac line coming from the back of the intake manifold . Hard as f**k to get at from the top . But I got it after a week of feathering the throttle with the tranny in neutral at stop lights

 

Try spraying some carb cleaner down the back of the firewall with the engine running . If this is your problem , your engine will rev up slowly

 

A vacuum leak would throw lean codes, not EGR or MAF codes.