89, 4.0,Spectre cowl intake, new plugs/wires, 389k mis( you read that correctly!!&#128556. Passed w/intake 2 yrs back. What I'm hoping for is an IN ORDER listing of parts I need to check/buy...... My smog readings that were problematic......my CO % was ZERO......my NO ppm measured 1677 with 711 max to pass. Everything else was pretty well below maximum limits. Thanks for any and all advice.....Pez

 

You ever replace the catalytic converter?

 

At least 3 of them over time but it has been a while.

 

Checked for vacuum leaks? Low CO combined with high NO means a lean condition.