I got an error code: "Missing fire #3" on my 2001 SLE bonneville. I need assistant on this code. Thanks

How old are your plugs, check your plugs and wires first.

After the error appears I upgrade my sparks to a Bosh Platinum 4 and bosh 10mm sparks cables.

I am not saying its the problem, I am just letting you know that bosch does not work well in our cars.