My car is hesitating badly,I have had a tune up,fuel filter changed, and intake replaced but, my car is still hesitating to the point where it almost stalls out.I have also had 2 diagnostic test ran and they told me it was the #4 cylinder miss firing but, this was before I had all this work done.
               2001 Ford explorer sport trac with 64,000 + miles

Optional Information:
2001 Ford EXPLORER 4.0 6 CYLINDER

Already Tried:
TUNE UP, FUEL FILTER,INTAKE CHANGE,