New Member, Looking for Assistance

[SubaRub]

Hello there my name is Ruben. I've been lurking around this forum for about a year now ever since I got my 1996 LS. This website has been a good source of information for me, so I decided to register in the hopes I might get help with an issue I'm having.

 

I'm currently experiencing a reoccurring misfire in the #2 cylinder, especially on long hill climbs.

 

The problem first started February of this year. The wagon started misfiring and I brought it a mechanic to have the CEL read. He advised me to replace the #1 cat. I found a bolt-on CARB legal cat and did the work myself. It was nearly a perfect fit, but the nuts connecting it to the exhaust manifold and #2 cat couldn't be fitted as snugly as before. I'll come back to this in a minute. At the same time, I replaced the Alternator, Spark Plugs (NGK Plats), & Wireset (NGK).

 

Up until November the wagon ran perfectly. Then I took the old bumpy dirt road to my friends house (couldn't resist). Towards the end I started experience a misfire and as I came to a stop the engine shut off. It would not restart until a minute or two later.

 

Again, I took it to a mechanic to have the codes read. Cylinder #2 misfire and the upstream O2 sensor. The mechanic performed a compression test which turned up normal. He advised me to have my fuel injectors cleaned, which I had done. I then replaced the spark plugs (NGK Copper), Fuel Filter, and PCV valve (I had these two laying around for a while and decided to finally get on it).

 

This worked for all of a week before the misfire returned, especially on hill climbs as mentioned before. The engine will run roughly for 10-15 seconds, and if I happen to hit a redlight in the middle of it and come to a complete stop, the engine will shut off and refuse to turn on for a minute or two just like before. My current guess is the initial jostling from the dirt road must've knocked around/broke something. All I can think of is the cat, since it never was an exactly perfect fit before.

 

But before I spend several hundred bucks getting one properly welded in place, I wanted to ask this forum if you had any other advice/leads that I should check out first.

 

Suggestions?