Jerky/Hesitation on 2002 Ford F-150

I have a 2002 Ford F150 with 39,000 miles on it V6 engine size. Recently I had the spark plugs changed and since then have noticed an occassional jerk/hesitation when driving. I do a lot of stop and go driving. It occurs after the enjgine is warm and about speeds of 40 or more. This seems to happen sporadically - two to three times in a half hour drive. Never noticed this problem before. Wondering if it could be a fule filter issue or just an issue of the new spark plugs being breaked-in. Prior to this I had to take the truck to Ford for an $800 repair having to do with a bad intake runner control valve. Any idea? I have a basic after warranty with Ford so am hesitant to have them look at it if its not something that would be covered.