Been working on Simon's car for a bit, and we can't seem to find a solution to his problem.

The car stumbles and bogs down at low RPMs and runs very lean up until about 5k rpm, then everything is perfect.

We've cleaned the MAF, changed plugs, changed the fuel filter and checked all the electrical connections.

We're puzzled as to what it is, any ideas?

-John


'98 4Runner