just throwing this in therre for the high, low rpms..... have you been power washing the engine bay lately? i remember some members having problems with water being trapped in the plugs for sensors. (look for thread by climbcovey) his wiring harness was having issues, but he had hi revs, and engine dieing, and after drying out all the plugs with spray, then using di-electric grease on all plugs, all those troubles went away.

Point two.......etl is right. I wouldnt drive very much, if at all if you are pouring gas down the cats. stock cats ARE VERY EXPENSIVE.. and as i am litterally waiting for mine to be MADE, it is taking a long time to get them. no one....NO ONE has a vehicross cat. converter in the USA. they are being made on order apparently from what isuzu of america customer service is telling me.
hope this helps someone...

david