Ecu reset on a machine ?, stop listening to whoever told you that!!
To reset the ecu simply pull the violet 3 amp fuse from the fusebox marked KAM, keep alive memory for a few minutes!
Anyway do the usual looking for air leaks, as sounds to be running lean when cold, the "T" piece pipe at the rear lower corner of the head on right hand side as you face engine is a fave pipe to split, collapse bugger up can cause this issue.
Other things you can do is clean the MAF with carb cleaner, the hot wires inside may be coated in general crap making the situation worse.
tabetha