Exhaust emission light

[tmdigitalart.com]

hi

just gone on a short drive,only bout 2 miles. when in second at bout 2k 2.5 revs slowly put foot down and it jumps allot and cant speed up.the exhaust emission light comes on and of.any ideas why its doin this,could it just be the cold,it has been allot colder recently and didnt have a problem.Also the window screen is getting real steamed up when first start up, think it really would take hours to get rid of if didnt wipe it, hardly any air cumin out the windscreen vent,with all others switched of and closed.

thanks for any help

tom