exhaust issue?

[pp5669]

I have a 99 F-250 extended cab with suicide doors. On cold mornings I hear a pulsating, sucking sound that is best discribed as an exhaust leak from under neath the passenger side rear seat. The RPMs drop as the sound occurs and then return as it ceases. The pattern continues until the engine gets warm. 2 dealers here in central GA are clueless on it

[Zaairman]

Totally normal. It's your EBPV.

Winter Operation, Hard Starting, Hissing Sound Etc...