A couple days ago my truck started to idle rough when I would come to a stop. It bogs every couple seconds and I can see the tach drop 200-300 rpm's. Once I give it some gas it runs fine. I tryed cleaning my DBW throttle body, but it didn't help. However, while I was cleaning it I noticed that it was not all the way closed while the engine was off. I could push it closed, but then it would swing back out just a little bit. Is this normal?

Also, while it idles I could see the throttle plate moving slightly every time it bogs. Could my throttle body be bad?

Any other ideas if this is not the problem? I was thinking PCV valve, but I couldn't find one, just a steel nipple that is pressed into the valve cover.

 

What the hell, my truck is doing the SAME thing. Mine just started last night and I'm thinking it could be my alternator, because I've been noticing the voltage gauge jumping around some, and when the voltage drops, my idle drops and the voltage goes back up. Does yours do the same?

 

your tb should be open a little bit even with the engine off, if it was closed how would the engine get air while at idle

when was the last time you checked/changed your spark plugs and wires, i know when i changed mine i noticed a much smoother idle

 

I get voltage drops when my electric fans turn on, but I haven't seen it drop while this is happening.

Plugs are still factory and wires are only about 6 months old.

Seems like the longer it idles the worse it gets and the harder then take off is. If I come to a stop just for a minute it leaves fine, but if I sit there for a while it is really sluggish and feels like it is loading up with fuel.

 

The voltage gauge does wave around some- this is due to the truck trying to maximize fuel economy and volt output during certain situations, i agree plugs first then if doesnt work try new wires

 

Just drove it again and it was starting to get really bad and then finally threw a code so i'll get it read and hope it is something simple.

 

I forgot to ask, but mileage on your truck? maintenance always or?

 

50k and I change oil every 3-4K haven't done much other than that.

 

good luck, hope you get it figured out

 

fuel pressure regulator most likely- plugs, wires and filter checked out will help, seafoam it!