I am really at a loss here and was hoping some of you guys could point me in the right direction for some do-it-yourself fixes.
Not really sure how to best explain the hardship I'm having with my 4-Banger, so I'll share some processes and assume you guys could get the idea of my situation from that.
1. CEL turns on with P0420
2. Replaced front Cat.Conv. and reset CEL
3. CEL turns on with P0430
4. Replaced rear Cat.Conv. and reset CEL
5. CEL turns on with P0420
6. Replaced front O2 sensor and reset CEL (sensor replaced due to failing test read on OBD-II scanner)
7. CEL turns on with P0420
8. Replaced front Cat.Conv. and reset CEL (previous new front Cat.Conv. was fried after <500mi.)
9. CEL turns on with P0430
10. Replaced rear Cat.Conv. and reset CEL (previous new rear Cat.Conv. was fried after <300mi.)
11. Currently no CEL, but could foresee that it will come on sometime real soon since both the Cat.Converters are already showing signs of excessive overheating (purple-pink-blue color hue starting to show).
Now here is my dilema or area in which I need help in, how do I fix the assumption that my truck is "running rich"? I was told by the muffler shop guys that usually the reason a cat.conv. goes bad sooo quickly is due to having an engine run "rich". They told me that based on their minimal knowledge of overall engine mechanics, usually a bad O2 sensor is the culprit, but since it's been changed out already, it's probably something up in the engine area that's causing the truck to run rich.
So what, where, how should I go about identifying any and all of the possible areas or components of concern that could trigger this "rich" running status? I'm not too great on mechanics, but can do pretty good with swapping out parts here and there if needed, just dont know where to start so to keep the cost factor down as best as possible.
Any advice guys?
Thanks in advance for your help!
PS: Just realized I forgot to include info on my truck... sorry guys!
2000 - PreRunner Xtra-Cab - 2.7 - 2wd Automatic