4.9 l surge under acceleration

[drainsf-150]

I have a 1990 F-150 w/the 4.9L straight six. What could cause this truck to surge while accelerating? <_<

 

[1992F250]

Many things. Need more details. Auto or standard? Auto may be your fuel system, timing, transmission, vacuum.. Does it do it in all speeds/gears? consistantly surging through out the range of RPMs? Engine Light on? You the original owner? did it come from another state? is it carburated/efi? Need more info

GL