Ford Repair: 97 ford E-350 5.4l drives like its out of gas, butterfly valve, abs light

Question
Hi, I have a 1997 Ford E-350 box truck with a little over 200,000 miles on it. Recently it has started to feel like it is misfiring (drives like right before you run out of gas). It seems to only do it when the truck is at a low rpm and I try to slowly accelerate. When i give it more gas it seems to go away. It doesn't do it when stopped at a light. I have changed the fuel filter that is under the chassis and it still is doing it. The truck is an automatic, it is gas, it has no air conditioning or cruise control its very basic. The check engine light has not come on (although the abs light is on even though i don't think it has abs)Do you have any ideas on what it could be? thanks

Answer
Have the Fuel pressure tested at three points.With ignition on, at an idle, and at around 300 R.P.M.Have the throttle body cleaned with intake and throttle body cleaner spray.The butterfly valve might be sticking from carbon.Also,how long has it been since you serviced the timing chain?