OK - still have the hitching/freezing. but I have conquered the mouse issue. is detected OK, but will freeze on the screen every few seconds. Similar to the middi issue I think.

Doom doesn't need IRQ or intelligent mode, just access to IO port for MIDI. The wavetable header is stateless so doesn't interact with the PicoGUS in a way that would affect timing. Can you check in the BIOS what speed the ISA bus is running? The PicoGUS has issues above 8Mhz

Does Doom show any signs of hitching on screen when there is MIDI issues? Does it go away when music is disabled?

Hmm...Thanks NeoG_ no way to tweak bus timings that I can see. Manual says 8.25Mhz. Could this be too much?
From the manual...This is a BX based board.
On the system board, the Intel PIIX4E provides the interface between the peripheral component interface (PCI) and industry standard architecture (ISA) buses. The chip set is used to convert PCI bus cycles to ISA bus cycles; the chip set also includes all the subsystems of the ISA bus, including two cascaded interrupt controllers, two DMA controllers with four 8-bit and three 16-bit channels, three counters equivalent to a programmable interval timer, and power management. The PCI bus operates at 33 MHz. The ISA bus operates at 8.25 MHz.

Is this the only soundcard in the system?
Are you sure there is no address conflict on the mpu port? ( Meaning 2 devices configured to use port 330 for example at the same time)

Hi.
I have an awe64 in default config at 330. Pico has been set to 300.
Tried swapping the slots around - only have 2 in this machine in case the shared isa/pci slot was an issue. Doesn’t seem to be as I have a lot of avail resources and it made no difference.

Popped in a SB16 Vibra with a waveheader. All works perfect with the X2GS TE...so it seem there is some kind of compatibility with the picogus and this motherboard.