Prior to giving it gas, go to 100% on your trim tabs, then full throttle. As you start to plane out, bring your trim tabs back to zero and then reduce the rpm.
Had a similar issue with my 5.0 MPI. Cause was a bad idle air control valve. Part for my engine was a two wire valve made by Ford. Exact equivalent was same for a 2002 Ford Windstar. Took about 10 minutes to replace.