Just had a clogged cat, it was really bad. Cut it off, and threw a new one on. Now my car idles funny, sometimes stutters. Even when I start it, sometimes no start. Almost 99% sure it’s opti but looking for second opinion. Car ran perfect before cat converter was clogged, now it’s all fucked. Also should I just replace the opti if I’m doing it? Not sure I could even get to my plugs to be honest.

 

When the engine is cold it is in open loop and will not take any O2 info until it goes into closed loop at operating temperature. You can also unplug the O2', start it up and see what happens.

 

From my own experiences in fixing my 1994 firebird. You will not have any injector pulse width if the opti is completely dead so id say hold off on changing the opti spark; dont go chasing ghosts. I recently have had issues where the engine will turn over but wont fire up, I was getting fuel, I fixed some grounds and a vacuum leak in the map sensor and it hasnt done it since. Now the odd time still does occur but it was not as bad and I have narrowed down the issue to be something with the evap system. The only time now it will take a second or two to start up is when I would crank it after being off all night and it is very cold. Since you said it ran fine and then now is running weird, I would assume the computer was once compensating for the heavy restriction, but thats my guess from what I have read through other forums. Try flashing the computer to see if it does anything.

I was able to change all of my spark plugs without taking off the manifolds however I did need to come up from under the car for some of the plugs and I had removed the shield that was near the starter. So you should be able to as well however it was extremely difficult and a slow process.