Originally Posted by scottydsntknow
Leakdown check on the cylinders. Could be valve seals. I'd try a heavier weight oil and see if that fixes it for now. Throw some Rotella 5w-40 in there.
See Scotty's advice.
2003 GT: JLT CAI, summit 75mm TB, C&L plenum, 24# injectors, Mac Prochamber, SLP LM1 cat back, 3.73 Gears, FR500 Diff, FR500 diff cover, Jmod trans and shift kit, Max Motorsports subframes, Koni oranges front and rear, DBA discs front and rear, shrader performance rear seat delete, APSX D2 wideband, MPT happy customer.