My Subaru seemed to be running rougher lately (81DL wagon) so I opened the hood and noticed that if I put downward pressure on the air filter housing the car suddenly seemed to run better.

 

I also discovered there was a minor amount of side to side play with the air filter housing (because I am missing a sidemount bolt) and I was able to find a sweet spot.

 

Anyone have an idea what is going on? I'm pretty certain the rebuilt carburetor is securely bolted down.

sounds like a vacuum of some sort somewhere.

 

I think I'd try to get that sidemount bolt and see if it helps.

 

you can also spray carb cleaner or similar sparingly in places. If the idle changes, there's a leak there and needs to be fixed.

 

good luck

Possibly a leaky carb gasket.

 

The 'spray it down with carb cleaner until you find the leak' is a good one. Do that and report back.

almost sounds like the 82 i used to have on mine it was the carb bolts had worked loose. try tightening them up and see if it helps

i would check all the phillips screws that hold the top of the carb onto the main body of the carb also. i had these work loose on a car i had once. turned out the whole carb was kinda falling apart right on top of the motor. tightened them all up and was as good as new...

My guess is that it is a Carter/Weber and the base bolts are/have loosened up. If this is true, you have to remove it and tighten them from the bottom.