I just fixed that same problem on my 98. Check between the battery and firewall. There is a vacumm line connector with 3 small and 1 large vacumm line. Mine had chaffed against the battery and wore a hole in 2 lines. After repairing the lines and resetting the computer all is well now.
( Mine ) 1998 F150 XLT s/c 4.6l auto ( 248,000+ on the clock and getting tired)
True dual exhaust
Covercraft soft tonneau cover
Deflecta-shield stone guard and wind deflectors
Cooper 265/75/16 ATR
( Hers ) 1998 Explorer XLT 4.0l ohc ( 147,000 on the clock )
4door 4whl drive
Last edited by Lou Colmo; 11-24-2003 at 02:21 PM.