I just recently added a Vortec VS-2 to my '99GT. Got it tuned up at NEDyno and ran 353rwhp - all was well (other signifcant mods are Magnaflow X-pipe and cat backs, Accufab TB 70mm TB and plenum). Injectors are 30#.
After a week the following started to happen.
After 5 minutes of driving...