Are you talking about the ones for the EVAP system, off the back of the intake plenum? If so, I'm surprised it had that effect: I found out this summer that mine were open / disconnected for who knows how long, and my truck ran great. As soon as I hooked them back up, ran like crap and pinged.

If this is the one you're talking about, it circulates recovered fuel vapor into your TB when the truck reaches operating temp AFAIK.

4x4Wire's Toyota Section
1995 FZJ80 LandCruiser - 3 locking diffs, +200k mi, JD HIR's, 285/75R16 Nitto TG's
Olde North State Cruisers