Hi.
I have an intermittent problem on a not so old Accord.

When going uphill the normally smooth engine starts to roughen. Acceleration also feels to be about 80% of what it used to be. Also, when this happens, a smell comes from the engine compartment - its hard to describe but like heated plastic, not a petrol-ly smell or burning oil smell.

Its a 4 year old Accord 1,8 VTEC engine and 52000 miles.

Any ideas? Thanks.