A few more questions ...

[Abraxsis]

So I bought my 01 Sport about 7 months ago, it ran amazing when I first bought it. Over the last 3 months my MPG has steadily decreased to about 16 mpg from the 20 I was getting at first. Also I have been getting alot more chatter (i assume this is valve chatter) when I first start the truck up, and also at the shift points. Over the last month I have changed the plugs to NGK Irdium IX plugs, switched the plug wires, changed the tranny fluid, cleaned the IAC valve/throttle body, ran Seafoam through the PCV hose, and added a KKM cold air intake. Still have rough idle when I first start the truck, and it is worse when it is cold. I still have good acceleration if that is important. I just dont know what else to do, I guess the next step is a new IAC valve. I scanned for codes and none showed up.

Any advice?

 

[Papa]

Hydraulic lifters can make some interesting clatter when cold. What kind of oil are you using and how many miles are on it?

 

[Abraxsis]

I have 5w30 in it, as I always use, and it has 83,000 on it. The clatter only started in the last 2 months, and I drove it all winter in extreme cold.

 

[Papa]

Try Mobile 1. Some Chevron Techron helped mine, along with a change in the weather. I get a 20 oz container at the auto parts store every now and then. The IAC can be cleaned if that is even the problem. The O2 sensors will keep the mixture a little rich till it warms up but a search will give you ways to check them.