I’ve got a 98 v10 that’s had a warm idle issue the entire time (a couple years) that I’ve owned it and it seems to be getting worse. After about 5 minutes after a cold start it starts loading up and choking. I’ve replaced the iac valve as well as the o2 sensors. I don’t know if maybe I just need new plugs and wires. But I’ve read that the plenum gasket is a common possible issue and I’ve noticed in the past few weeks that it’s been consuming oil which makes me think this may be what’s wrong. Any help greatly appreciated. Thanks

 

Your truck doesn't have a plenum gasket. At least, not in the sense you are thinking. Sure, you have a two-piece intake, but, where the joint is, there is no oil.

What brand O2 sensors did you install? How old are your plugs?

 

I used the denso brand ones. For about a week or two the rough idle seemed to go away but it has since come back

 

Unplug the O2 sensors, and see if anything changes......

 

I’ll give that a try and see what happens. Also idk how old my plugs and wires are. For all I know they’re original

 

May wanna change those then. Stick with standard copper plugs. These engines don't like the fancy rare-earth fellers.

 

Just put all new plugs and wires in over the weekend and it’s still idling rough. Kind of at my wits end with this truck. If there’s something I might be over looking or if maybe I need to replace o2 sensors again maybe. Any help greatly appreciated

 

How old are your O2 sensor? Did you try running it with 'em unplugged?

 

Just replaced them this summer. Just unplugged them and drove around a while, check engine light didn’t come on until the engine got up to temp. Don’t know if that’s normal or not. After I got it up to temp then I sat and let it idle for 10 minutes or so and it seemed to not want to idle rough like it had been before. Does that mean my o2 sensors need replaced again or is it something between there and the engine?

 

What brand O2 sensors did you put in? If they were Bosch, good change that is your problem.