53 Mercury won't run smooth at highway speed

Hello everyone, I'm Michael and I may as well be a "New" member. Been a long while since I posted. I need your help now so here I am.

I have a 1953 Mercury flathead V8 in a '49 Ford Coupe, that won't run smooth when trying a Steady speed. Fast or slow speed, the engine wants to surge or hesitate and not run smoothly. It's just started this and I have searched on this site to see if I could find an answer but NO.

If you can help I'd appreciate that.
Thanks a lot. Michael.

 

Put the choke on a little and see if it gets worse or better.

 

Welcome from North Alabama. I bet you have what is done on a lot of flat heads. Your timing is set to high. or your vacum advance is not working and some one added to much inital timing. Rember a FH is not a small block chevy.

 

Hi. Perhaps a vaccum leak. Just guessing. Jimmie

 

Check fuel flow & filter.