Ok, it cost me $118.72 US to have them tell me my Modulator valve (the thingy under the airbox) has an internal failure. $900 US to replace, parts and labor (Pontiac Dealer). They extracted codes 33, 37, and 41 in the process, I think 33 and 37 are the rear wheel speed sensors, but the mech said they actually checked out fine, including the whole wiring harness, so he thinks they're bogus codes. Anyone know these codes for sure? Speedguy, you mentioned high pressure bleeding solved your problem (remember my car sat garaged for 5 years), and the dealership said the Teves Mark IV system is a bitch to bleed.....15 times each wheel, then repeat the process, 4 jugs of fluid.
Any thoughts? I'm thinking if bleeding doesn't work, I'm gonna try a junkyard part with a 30-day warranty, but it'* gonna be hard to find a PMV assembly from a 91-93 Bonnie that had both ABS and Traction Control.