I just bought this 1998 ranger about 2 weeks ago. have spent about 10 hours trying to diagnose this rough running at idle/ vacuum leak/ other issue with my classmates, (im in auto tech school) my teachers, and the master techs at the shop I work at. So far we have knocked off the egr, as it functions properly, the pcv was what we thought the issue was and so we replaced the valve and clamped both ends of the hose as they were a little loose. nothing. still runs like dookie. BUT only when it HASNT been driven???? when I take it on the freeway (because its the only car I have) it runs fine. BUT SOMETIMES IT HAS NO FUEL RESPONSE? floored and it doesnt do anything. then i repeatedly floor and let off and if i do it enough jt comes back. i dunno. makes me wanna kurt kobain