1994 Z71 Surging, Running Lean
 

Guys, I have a 1994 Z71 extended cab. It sat for several months before I bought it and I have fixed quite a few things so far but I have one major problem I can't seem to diagnose and it is getting worse over time. I first noticed this probelm after I had all the tranny removed to replace all seals/gaskets. The longer the pickup sits the more likely this problem is to occur. If I drive it every day it usually won't happen. But when it does, it starts with with the parking brake light illuminating. Then it will begin to surge at low-mid rpm and completely lose power at high rpm. If I then let off the gas it will shift and sometimes resolve after a few times during the drive and sometimes continue on even through idle. Sometimes the speedometer will jump around sporadically. The only other info I have for you is it is throwing a running lean code, the temp gauge needle hardly budges from its original position, and occasionally I can smell gasoline outside of the vehicle. I have not been able to trace the smell but it is definately gas and nothing is dripping on the pavement. Thanks for the help!