Removed and cleaned and reinstalled flame sensor Removed and cleaned and reinstalled gas burners Checked gas outlet pressure Checked igniter Checked filter needs replaced Inspected and tested inducer motor and blower motor Checked your condensate drain trap Furnace has some issues: Rusting on the inducer assembly area. Potentially caused by leaking gasket or cracked inducer assembly Inducer is struggling with load Replace inducer assembly and motor on the 18 year old furnace or consider replacement verses repair Customer agreed it would be a good idea to have dan Fox out on a second opinion to quote parts cost v replacement cost.