96 Jimmy running rough

I have a 1996 Jimmy that recently started running rough. The first time it happened the car would not get up to speed. I smelled a burnt rubber smell for about 5 seconds and then my check engine light came on. I continued to drive and it smoothed out and kind of sped up all at once, but still felt a little bogged down. Now the check engine light comes on and off. Most times when I take off it struggles a bit, but other times it seems fine. Going up large hills really bogs it down and can also cause the engine light to come on. Yesterday at a light it was sputtering and seemed to be idling low. Then then it quickly burst the idling up and the check engine light came on. I only smelled the burnt rubber smell the first time this started. Before this started the check engine light used to come on and off, (mostly off) for o2 sensor even though I had all three changed. Now the engine code reads O2 sensor and misfire. Any help would be greatly appreciated.

Common problems are the egr valve clogging with carbon. I would take it off and look for chunks of carbon and the cpi is also bad about leaking and causing the sputtering. My engine would rev up and down and it was the cpi. I also had the problem with egr and fixed that also.

thank you,

I will try that