i have a 2k rodeo with a new motor. I cracked the block at 51k and had a new motor put in. I have issuse with the new motor and isuzu has no clue how to fix it. I am tired of taking it back. I took it in because it had a rough idle and was getting crap mpg 12! from the normal 18. They replaced the IMG and it was good for one tank. first tank 17+ the second was 14 and the third was 12. After the I took it in and they had forgot to hook a vac line to the fuel regulator. Same thing got it back and 17--15--12 mpg. Mind you I only drive freeway to work and back. So the driving conditions have not changed.
now they don't have a clue what it is. oh and it gives no codes.

I almost forgot. sometimes when going from drive to park it drops rpm or dies. Or it goes up to 1k for a second. In the mornings the idle is not a fixed high idle it can pulse a bit.