Well I'd start with the basics. Get some MAF cleaner and get her nice and clean. It really helped my rough running problems. 91 motor in a 79 rabbit.
Ok first off I know this isnt the cabby section but MK1 has more people.
Working on my wife's 89 cabby prepping for winter. 3 issues;
Only the defrost works... Slide the adjustments to anything else and nothing happens. I looked inside the dash section and the cables look good up top... What do i need to do down below? Also the defrost has a slight "Burnt" smell. Not like leaking coolant but almost like over worked if that makes sense.
I replaced the vacuum lines under the hood and now you can hear it sucking air from somewhere inside the car (only during vacuum according to the "Bar" gauge.
Random issue: every now and then when you start the car it cuts in and out. never dies but idles really low and you have to really work the throttle to go any where. Then after a little bit it will kick right up and run flawlessly. New intank pump and fuel filter. still doing the same thing...
Any help would be appreciated
"So stick that in your Juice Box and Suck-It!"
"Excuse me Sir. Sir! This is not the designated parking area." "I don't give a DAMN!"
Post in the cabby section. Brains and many others there are super helpful. Your HVAC system is vacuum controlled so a vacuum leak would explain a few of your issues. If you have ac, you need the black bubble pack under your hood. Its a vacuum reservoir and it keeps your HVAC system from changing with different engine vacuum.
Your CIS injection is very sensitive with vacuum leaks which may explain your engine trouble
1.6 NA diesel all day baby!