my 900 mile 4dr Civic Si surges at moderate throttle when cold. I am in wisconsin its about 20 f. in morning. I run 93 octane. It cleans up as soon as engine is warm. I asked service department and they came up with no hits in database. I am hoping that somebody has a suggested fix rather than have them blindly checking everything. Any advice?

As some background information, I have a scanguage and 1. it does not surge in open loop, but with closed loop I can see that instantaneous cold gas mileage in town is down about 10 mpg when surging happens (water temp less than 100f.) . So, it seems this engine is running rich at that time. Once wrmed up, same conditions would give me 20+ mpg and smoth acceleration . Again any advice on what to investigate is appreciated.