1998 Ford F150 Poor Engine - skipping

My Ford F150 is fine when I first drive it (10 miles) then it begins skipping, lagging at take offs. If I go at low idle speed it is fine but begins to skip when I give it gas. It does not cut off if I give it enough gas - however it will skip and then take off. It sort of 'shutters' at full throttle.
Thanks for any help - laid off and need this transportation!