My truck starts up fine in the morning. I drive about 4 miles at about 50 mph when I come to a stop a the traffic light the truck dies. The tach goes to a normal idle and then drops and dies. I starts right back up and will die if I let it idle. If I rev it up a little it runs fine. I will die at two or three more lights on my way to work. By the time I get to work it runs fine with no dying. It runs fine in the afternoons with no dying. If I drive it late a night it will die at lights too. It seems like the colder morning and night temps may have something to do with the dying. I replaced the IAC motor thinking that was the problem. I didn't work. I am still having the same problem. What else could it be? TPS, cam sensor, crank sensor? I don't want to just keep throwing parts at it hoping it fixes it. Please help

 

Pre-cat oxygen sensor, almost certainly.

 

sounds like your IAC

 

I could buy that, it did briefly cross my mind.

As I said above I just replaced it. I tried cleaning the old one and when that didn't help I replaced it. I am fairly certain that the IAC is not the problem.

 

years ago I had a 318 that loved to do this..
I did everything I could think of to fix that dang thing and come up short- the biggest reason is after a while of running it would run just fine...
It wasn't hard to start at first, but it was sure hard to keep it running..
Then it started being hard to start...
Then I killed a charge or two trying to start it and had to jump start...
And then one day, a Saturday morning when I didn't really have anything to do, it did it..
Cutting this tale short, it was an almost invisible crack in the distributor cap that was allowing condensation in the thing.. and it would cook off during the first ten minutes or so of running, only to do it again after it sat a while, and usually overnight. (morning starts)..

If all else checks out, check this one.. It sounds almost precisely like what I went through... I never even thought to check the cap, until I did, and the rest is history.. We often think of them failing all together (rotor button), but they sometimes do just like that one did me..

Is your engine difficult to start?

btw: the only reason I found that crack was because I had determined it was electrical, and pulled the cap to look at the points.. and caught myself wiping condensation away to see them.. Yeah, it didn't strike me as odd at first as strange as that sounds.. When I went to grab a towel to wipe it out is when it hit me... DOH!! (one of those 'A-HA YOU DUMMY' moments..)

 

No not at all. In fact it starts great. It runs great except for dying at traffic lights. Even after it dies it starts right back up. No check engine lights either. With my scan tool hooked up all the live data looks good too.

 

Crank sensor.

 

got any codes ? i had a similar stalling problem. it would crank right back up and run on, and if i kept a little pressure on the gas pedal, i could generally keep it running. after a couple of days it showed a P0123 TPS code. new TPS fixed it.

 

No codes at all. It would sure be easier to diagnose the problem if there were codes though.

This problem started a couple of months ago. I did it died oned and then about 3 weeks later it died again. Now for about the last two weeks it has been happening nearly every morning on my way to work. Like I said earlier it runs great in the afternoon. I have no other drivability issues except first thing in the morning at stop lights. The truck runs prefect other than that.

 

I'm about 98% certain that it's your pre-cat oxygen sensor punking out. They often fail without setting any codes. One user here had been fighting a similar problem for months, then when he was on his way home with the new sensor in his pocket a code was finally set.