So I put together the Am386 on the EXP mainboard I have with a 1 Gb seagate IDE and 4 Mb RAM and I've been playing Settlers for hours now and it seems to be working. I used the existing IO board and ISA video card (sadly, my Mach32 VLB is no good) so it has got to be the mainboard of the system.

It's been mentioned before... doulbe check the jumpers.

I will inspect the old board thoroughly.

Could be a fried MOBO. Nothing much you can do about that. Except replacing it.