So I started up my car this afternoon and my car instantly started chugging. The RPMS would not stay stable but they never revved high, always stayed under 1,000 rpms. You could tell the car was dumping a lot of gas into it as there was an excess amount of exhaust. After letting it idle about 10 minutes everything leveled out. I then drove to the bank and back with no other symptoms. It was about 20 degrees today and got down to about 5 last night (windchill's were 5-10 degrees lower). Does this sound like a spark plug problem? I mention the plugs because that was one of the only things I did not have the dealer replace when I brought it in. I hope someone can help. This has me a bit worried.

FYI, just got my timing belt replaced, water pump, tensioner pulley, valve adjustment and all drive belts done at my local Honda Dealer.

 

If you are describing the engine was going up and down in RPM(hunting) and just had work done on the cooling system(water pump) my first thought is air in the cooling system. The temp sensor in the engine would send the wrong signal to the computer for engine temp. but the RPM will go up and down rapidly. Is that what you have?

 

I got all that stuff changed about 4 months ago so I am thinking it is not the cooling system. I am thinking that I may have got some moisture in my gas and as we know gas floats on tops of water and that caused it to run so poor. After about 10 minutes it was fine. Never had that problem before. I am going to start up the car later and see how it runs. If it is doing anything similar I am going to buy a bottle of Heet.

 

Have you considered your motor oil?
This may sound over-simplified, but cheap dino oils are very thick and sluggish in cold weather conditions. Synthetic oils circulate much better in the cold. 5 deg temps could have been the cause by themselves. If you're not using synthetic oil, consider it.