It sounds like the problem is probably in the instrument cluster itself. The printed circuit board on the back of the instrument cluster itself gives a bit of problems on these vans. That's where I would expect your problem to be. A quick fix, when it's acting up, turn the key on and give the dash a decent smack right over the top of the cluster. If it comes back on you know that's where the problem is. If that doesn't work you would need to pull it out and check powers and grounds and communication bus voltages, which I can help you with if you have a meter or test light.
What happens is when the cluster goes down it will short the communication bus system to a higher voltage and it stops all of the modules on the van from communicating with each other. This explains the abs light, engine light, and the fact that the trans controller can't talk to the engine controller.
If the circuit board is the problem there are a few choices. You could have the board replaced. It runs between $4-500 plus calibration. You can also normally pick up a whole used cluster at a salvage yard for about $100. If you're handy with a soldering iron you may be able to fix it yourself. There is a problem area on the boards where the electrical connector terminals solder to the circuit board. If you pull the board off the cluster and look at the other side you will see the solder joints. With a magnifying glass or microscope check out these joints for cracks. You may find these solder joints are cracked and causing the problem. I had one of these apart a few days ago and the joints were cracked enough I could see them with a naked eye. If you can find the cracks in the joints solder them back up and see if it works. It's a heck of a lot cheaper than a new one!