Fews days ago flashing engine light came on and cylinder 8 was misfiring . I replaced spark plug and ignition coil and engine light didn't come back.

I notice a strong rattle sound from right side of the engine when I cold start it and also when I start driving it in slow speed. the sound goes away after warm up.
It also has power problem while going up hill. So I was wondering if catalytic converter is bad? I have p0442 light on for small leak too.

My question is : Can I install universal fit catalytic converters? OEMs are way too expensive. I probably need a extension tube and clamp to fit it or may be weld it?

Ford E-250 2000 5.4L V8 Gas. 73k miles

 

FYI , the EPA has some strict requirements when it comes to replacing catalytic converters. Some states will also check if the emission system has been altered before passing a vehicle for emissions.
Because of the expense involved , you might want to have the system checked and you may not need to replace any converter..

 

Mine does not need any inspection

 

This gets a little hairy.
Right now there is a vapor emission problem. If the light doesn't bother you and no inspection, your choice.

If however there comes another problem aside from power you will never know because the light has always been on
I cannot tell you or direct you what to do to render any emission system inoperative or delete them , that is why I say , your choice.
Not knowing the condition of the vehicle, but only 79K miles,it's just broken in !
If you can see the inside of the converter you might be able to see if it is somewhat plugged.
You can also hook up a vacuum gauge to manifold vacuum and watch the gauge as you raise and hold the engine RPM to approx 2000. . If it comes up and stays steady, no restriction. If it starts going down lower and lower there is a possible restriction in the exhaust system.

 

The code could be something as simple as a bad gas cap. I wouldn't assume the CAT is bad until you verify it with your vacuum gauge..If you drove a long time with the misfire, then that could have melted the internals for the CAT. A rattle can come from a shield, even if it is coming from the CAT, it still can be functioning. Low fuel pressure can also cause your drivability issue.

 

I have replaced fuel pump, fuel filter, all spark plugs, vent solenoid , purge solenoid, gas cap and still can't get rid of this small leak p0420 error. PIA

 

Yesterday I checked temp on both ends of CAT and I doo see a diff of almost 100F so looks like CAT is working fine then.