Ok fellas, I initially had a bad coil and plugs. That has been remedied. The 420 code lead me to r/r the O2 sensor on that side. There are only 2 remaining O2, one on the other side and after the catalytic, Correct? The remaining work to solve this would be the cat and/or O2 after the cat, right?
Thx for helping a tool starved mechanic...