My 2001 ls is miss firing on 1 2 4 cylinders and it is running lean
by Visitor in Lakewood, NJ on February 21, 2011
Repair your misfire first, then re-assess the fuel trims.
If you have the 3.9L V8, your coils could be the issue. There could be an oil leak at the valve cover gasket that leaks oil onto the coil boots, causing deterioration. This is a good first place to look.
On the 3.0L V6, you still have coil on plug, but not the oil leak issue. Still, a misfire could e caused by faulty coil boots or plugs.
At first it was only # 4 cylinder and I put a new coil on it and it started misfiring 1 2 and 4 and I did not see oil on the boots I have the 3.9L v8 and i put new plugs in all 8