looks like he did swap in the 4.3TB from this thread:
http://www.4x4wire.com/forums/showf...mp;amp;sb=5&o=14&fpart=1

you should not need a different ECM. but, if you want to try an ECM from a 3.1L, i do have a spare you are welcome to. just shoot me a pm or email. but again, it shouldn't be necessary.

Quote
Did you put on a 4.3 TBI with the swap? MY old TBI from the 2.8 wouldn't run the 3.4
It only got better when I put the TBI from the 4.3 on.
After that, check the vacuum hoses and such.
Shouldn't need another ECM

1992 Isuzu Rodeo 3.1L(now 3.4L) V6 4x4