I ask about the MAF cuz it could be MAF overrun.. depending on what you mean by modded MAF.
Might want to try replacement wires (you can always return them) just in case because that would cause stutter and a freaked out o2 voltage.
Later...
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Mike J-Quadcylla-92 Laser RS-T, FWD
Vortex Racing http://www3.sympatico.ca/robin.jackson2/HomePage.htm Alt Email: vortexracing@hotmail.com