Not having a charcoal canister with the purge control still in use makes sense. 

From what I understand of this setup is the charcoal canister collects vapour from the fuel tank vent system which is then burnt off in the cylinders when the ECU determines the right conditions are present - usually a cruise and light load revs. 

No charcoal canister means no vapours which is effectively just sucking air and leaning out the fuel mixture. Add in a faulty valve that could be open all the time and you get your stumbling revs/misfire like running symptoms. 

I got ahold of a canister from an ‘83 today, and will try the your hookup layout, thank you! It feels like several symptoms are explained by the lack of charcoal canister.

Full disclosure, I had eliminated the canister five years ago when the 2.2 was installed to my 83 wagon. Because that swap had worked well, I just forgot about that until I saw the canister I picked up today. Which reminds me of having seen it in the original donor car.

 

Checking in to keep this string alive, I am wanting to get back to the brat with the addition of a canister in the loop but have been pulled away in other directions. A good goal for me is to close this issue in case it might help someone looking for solutions in the forum.

First task will be to tighten up the trans shifter as it won’t let me get reverse. When putting the 2.2 in, I added some plastic sleeve material to the bore in the trans shift rod to take some of the slop where the ball end of the shifter seats, and didn’t see any bad wear in other sleeves but that didn’t work. I need to change the grease seal on the trans shift rod anyway. I think I’ve finally gotten the correct seal in hand. Fingers crossed, I can take care of these things and then get back to fuel vapor pressure and purge control.

Thanks for advising.

I added the charcoal canister between the gas tank and vapor intake on the 2.2, plumbing the vacuum valve per Bushytail’s advice. Viola, all is well. No more excessive tank pressure, no more bucking. An aside to the main topic: The shift mechanism on the old 4mt was fixed with tapping threads clean through the sleeve, and shift rod. Really is the ‘gold standard’ to fix this. For anyone still using the four speed.

I sure took the long way around to get this fixed. Just couldn’t let go of the fact that the 2.2 ran fine with no canister in GL wagon. But many thanks to all here who helped me to get this Brat running right!

 

The fix for a sloppy gear stick/shifter is cut a slot in about 20mm approx, parallel to the shaft’s location. Make the width a few mm at least. Do this on each side of that bracket. 

Then drill out the hole on the bracket while on the shaft so both are done at the same time. Shove a bolt in it with a metal lock nut, tighten the living daylights out of it and you’re done. 

If the gear stick is still sloppy but in a different way, you need to replace the bush on the bottom of it, the one that sits in a cup on top of the gearbox. Access this via the cab with console etc removed. I’m yet to do this, I was told a bit of garden hose over the end of the gear stick placed back in the bush does the trick. 
 

Well done on sorting out the running issue! There must be something in the mix on the old setup that does something that the charcoal canister does now.