'63 544

An intermittant engine hesitation started suddenly about a month ago. An oily substance was noticed in the fuel at a glass housed fuel filter between pump and carb. The filter element was replaced but quickly fouled again. Suspecting the pump diaphragm was leaking, the pump was replaced. There filter fouled again but not quite as quickly.

I then figured that some bad fuel (or some diesel mix) was being dispensed at a friendly service station. The fifth fuel filter element in three weeks seems to be staying clean. The engine hesitation is almost entirely gone and the car pulls strong under load.

The car still bogs after a quick decelleration to a complete stop. If the choke is pulled out, then the hesitation goes immediately away. The choke can then be let off and the engine is fine again until the next quick stop.

New: Plugs; Fuel Pump; Fuel Filter; Air Filters
Plugs and Points recently gapped
One entire can of carb cleaner applied to outside and inside of carbs.

Any suggestions as to what to check next are welcome.

Thanks,

Joe M