its either the o2 sensor is bad or the pre cat is bad,] if its the cat then your in luck cause they have a 80,000 mile warnty so give the dealer a call
98 svt sil/blu 3.0 oval heads full P&P, msds headers,bat kit,2,1/2exhaust 30 inch glasspack and 2 spintech mufflers 14.78@94mph
with my mechanical arm i can shift gears in less then a twentieth of a second for sale $7000