Mercury Marquis Trouble Codes

Hello, I'm Not 100% That I Have A 4.6l Engine But Anyhow. I Received Two Error Codes And Cannot Figure Out What They Mean.. I've Tried Just...

I Installed A New Spark Plug After It Blew Out Of The Engine Cylinder Head Like The 4.6 And 5.4 Ford Engines Are Known For. I Used A Heili...

The Check Engine Light Is On, My Scanner Shows A Code Of P0430 Which Indicates A Possible Bad Catalytic Converter Or A Bad O2 Sensor. Don't...

Just Bought This Car That Has Not Been Driven For About Two Years. I Completely Ran The Car On That Two Year Old Gas Before I Refueled. ...

It Started As Codes P0305,p0307. Misfires On Cylinders 5 And 7. I Purchased New Coil Packs For The Two Cylinders And New Plugs For All 8 And...

I Recently Had The Po 420 Code Show Up On My Grand Marquis. I've Replaced The Downstream O2 Sensor On Bank One. It Didn't Fix The Problem...

Code P0430 Keeps Engine Light On All The Time. Have Been Told By Others It Is A Bad Ox Sensor And Won't Do Any Harm. Is This True? And...

Catalyst System Efficiency Below Threshold Bank 1 Is What Shows Up. Took It In Auto Zone Did A Diagnostic And Showed Cadalack Coverter. But...

Could Not Smog Car Because P0174 Code. Took It To A Mechanic (ford Doctor). He Replaced The Intake Manifold. ( I Know The Story) Gorman Made...

Replaced O2 Sensor Bank 1, #2. Reset. After 100 Mile Drive And 2-3 On Cycles Problem Came Back. Reset Again And Problem Comes Back. Checked...