F150 coughs every 35 sec.?

[snorklebob]

I have a 2008 f 150 that has started coughing once every 35 sec. at any rpm. Is there a part of the motor which rotates at a steady rate [ say 35 sec] that might be the reason for this hiccup? I have put a light on each plug and it is not missing. I have pumped the ball and held it while every 35 sec. I get another skip. Starting to lean toward a mechanical problem. Any thoughts would be appreciated.

Thanks

 

[99yam40]

maybe the skip you are speaking of is a lean sneeze.
I would clean the carbs and look at fuel related things

 

[BaileysBoat]

This is interesting, noting that you have an EFI engine. What are your WOT numbers?