My 2002 GLS with the V6 just started doing this today. In park, the car idles a bit rough. Once the car is in gear or the AC is running in park, the roughness goes away. There are no "check me" lights on in the car, so I guess that means nothing is creating an error code, right? It has 61,000 miles on it, so the plugs could probably stand to be changed, but I'm thinking maybe it's some bad gas...? Is there anything else I should be looking at?

I should add that my wife drives the car, and she hardly ever lets it idle in park, but doesn't recall this happening last week before she got gas.

 

bump for the same problem, i'm throwing a P0171 & P0174 for lean mix. I've cleaned the throttle body, MAF, checked everything for a leak? Any chance it's the fuel pressure regulator??

 

i would do the plugs, even if it's not "time", they still have 61K on them.

i'd also look for a slight vaccuum leak. with the motor running, gently squeeze the hoses, especially around the throttle body and listen for rising RPM's. you can also spray some choke/carb cleaner on the hose and listen for the rise.

i would also replace your PCV valve (or clean it very well), and wipe the inside of the throttle body to get rid of carbon buildup.