Do you have a sample of this output when things were all right? You need to check performance tools enough that you can recognize changes. I don't use SCO so I can't give very specific advice but the very high wio stands out like a sore thumb and the first thing I would suspect is disk. That mpsar thing seems very close to sar and so there probably is a -d option which you could try. How about iostat, is that available?

And check any error logs very carefully looking for disk soft errors. Disk drives can slow to a crawl when they recover from soft errors. If the disk is recovering from soft errors now it may soon fail completely. This is especially true of ATA (aka IDE) disks which I'm guessing you have.