Any idea from anyone why my engine starts to skip after about 50 miles of travel at 60 mph?  Seems like it simply shuts off for a couple of seconds then runs, then does this off and on for a while.  Then straightens out and runs OK for a while before starting up again.  Worked on the fuel tank last week.  Could a fuel filter be the cause?  I would think a clogged filter would slow the fuel all the time and not intermediately.  Any other ideas on what to check?  Haven't changed plugs in a while.  Can they do this?  If I depress the accelerator while all of this is going on, things seem to get worse.
George