vacuum problem?

1995 940 2.3
Hi all, had what I thought was a vacuum problem (uneven idle, idle speed affected by brake useage, fuel consumption dissapointing, sluggishness). Car was fitted with hand controls so I removed them to reduce size of vacuum system and eliminate from enquiries. No difference. I can get a swing of 400rpm going by rhythmically applying the brakes whilst at idle. Checked all around the induction side of things using the dodgy 'can of propane' method but heard no associated change in engine note.Re-connected vacuum tank that came with the hand controls to increase reserve of vacuum but still no difference - any ideas?
Pete.
88 740 2.0 estate man
95 940 2.3 estate auto

[Peter Milnes]

Have you tried the non-return valve on the front of the brake booster? Do you have air conditioning? Have you cleaned the inlet tract (from air filter to manifold, including Idle Air Control valve)? This should be done every two years.

All the best, Peter

thanks for responding Peter.
No aircon.Looked at the air flow sensor and everything looked clean but I'll try your suggestions.I also get a 'stutter' or hesitance when I depress the accelerator ...? Most of my knowledge is 740 based so I'm going to get a manual so I can get to grips with the air/fuel management system.
Peter

[vjck_uk]

Are you sure it's not just a badly set-up on the engine,if the fuel mixture is weak it's going to be a lot worse when you touch the brakes,that couple to the crap running could be worth investigating.
Try the brakes when the engine has been stopped for about 30 seconds,if the servo still has a vacuum in then you know there's no leak on the buisness side of things.