I have a 1994 Mitsubishi mighty max. The collar on my fire wall where the clutch cable fits into and allows me to adjusts the tenson has pulled into the cab. I’ve fabricated a plate on the firewall with a new collar but I still have to much slack on the cable. Any ideas?
Nice truck! How many random offers do you get under your wiper blade from strangers wanting to buy your truck? I get several per year. 
What’s stopping you from pulling the collar back out of the cab?
I had a VW Rabbit with a clutch cable which broke, so maybe that’s the problem. If the cable remains intact, it might need to be lubed. I had that problem with the Rabbit too. If your fix at the firewall was done correctly, then it is configured exactly as it was new, so maybe you just need to adjust the clutch cable tension following the shop manual procedure. I had to do that w/my VW Rabbit too occasionally. Typing this I’m re-appreciating the benefit of hydraulic operated clutches … lol …
Shim under the plate to remove the slack.
This is after I got the plate on 
. I was able to break the old collar off and had a friend at Michelin weld it onto a plate. I have it wedged behind those break lines on the fire wall. My problem is the collar is supposed to be at say a 45° angle but my friend welded the collar on at a 90°. It “works” but I can’t get the tension right to get into first. Also tried to wedge a spacer behind the plate but I have no room unless I move the break lines
Having something wedged behind (brake) lines sounds like a good way to make those brake lines break.
I’d focus on coming up with a method to return that collar angle to what it is supposed to be. Don’t monkey w/it further, just go back to the welder for a re-do.