Frustrated, need all sorts of help
So a couple months ago I had mid length headers and catless H pipe installed on my car. I was still using Bama at the time and I was having problems with my o2 sensor on the right side. My check engine light would come on and off, but I didn't notice any issues with performance.
About a month later I took my car back to the same guy to have him install my 3.73 gears (stockers were in there) and have him perform a street tune to see what life without Bama was like. He also switched the o2 sensor from the right side to the left side because I was a cheapskate at the time(the light only came on once since indicating a problem on the left side now). The car drove great for 3-4 weeks, and then my aggravation began.
First, I was driving the car rather aggressively the other day in 4th gear and my car got to about 4500 RPMS and the car felt like it hit the rev limit. I shifted to 5th gear and same problem at about 5000 RPMS. Then a week or so later it happened in 3rd gear at about 4500 RPMS. Is this because of the 3.73's?? Now the more I drive the car, the stronger the exhaust smell is getting. The smell is obnoxious now. Smells like it is running rich. Finally 2 days ago my check engine light came on. I ran the code and it came back P0030 (Random misfire). I did change the coil on plugs and plugs a few months ago but I have never had a problem. Checked everything and it seems tight.
Not really sure where to begin? I guess I should call the guy that did the work. Anyone else have any of these problems with similar mods? I'm nervous I'll have a big repair bill. Any help/advice/ideas as to what it might be will be great.
2015 F150 - daily
2015 Focus ST - sold
1986 Mustang Saleen clone - new to me
2013 Mustang GT - sold