Hello everyone, new member but not a first time audi owner, have had a 92 100s and a 91 cq (best car I've ever owned)

Recently purchased a 95 90q for $1200
Pearl paint in great shape with only a few small rust spots on the door edges
Interior is a 9/10, leather in great shape with no rips at all, headliner perfect-no sagging, all windows and sunroof work
High miles -228,000 but still running strong
Has original exhaust which is rusted pretty bad with multiple holes, but i have a replacement to be put on with a single high flow cat and stainless can, most likely pretty loud.

Front right outer cv boot is torn, ordered a whole new axle, have been told its easier to replace the whole thing instead of just the outer joint.

has new calipers and pads all the way around

Clutch and tranny seem tight but unknown when replaced last, also timing belt/water pump are unknown when replaced last.

Questions:
It has a slight stumble when accelerating, also idle is erratic sometimes going close to 2k and sometimes dropping low enough to stall. Thinking this may be due to holes in rusted exhaust causing crappy back pressure-also plan on changing the plugs today with bosch platinum +4s
Is seafoam a good idea with these cars? I use it on my bike all the time and it really helps with cleaning out carbon deposits

Is there something else i should look into about this hesitation/stumble?

When decelerating sometimes there is a single clunk coming from what seems to be the tranny? I know that these cars make plenty of noises, just curious if its something i should get under and check out and where to exactly

Is there any thing else I should check into? this car was mainly bought strictly as a from town to mountain car during the snowboard season, so if i can get through the winter with it ill be happy, but at the same time audis are in my blood and the longer it runs strong the better.

Thanks for any help and thanks to this site for its vast array of info.

Im located in Burlington, VT

 

Clunk could be a bad tranny or diff mount. For erratic idle, I suggest cleaning your idle stabilizer valve (ISV)with carb cleaner. Sea foam does work on these cars.

 

Pulled from another post - I am not 100% sure as to the reasoning (or to the truth behind the statement), but there is a lot of history and questioning as to spark plugs on this forum for one reason or another, might be worth heeding (or researching more):

[Spark Plugs]:
"NGK BKUR6ET-10 are recommended but so are the triple prong Bosch copper.
Platinum plugs are not recommended."

Best of luck and welcome - I'd try to write more up for you, but I am currently immersed in a serious oil leak on my end (and don't know that much). Hopefully others will chime in to offer advice as well.

Also, there is a whole heck of a lot of info in the annals of this forum - search them out, there are many great write ups.

Lastly, the Bentley manual (CD), is by far the most comprehensive manual for this car - worth the investment.

Chuck