94 Buick RoadMaster Estate Wagon LT 1 issues

[Bentwings]

One more small issue has come up.

When coming to a stop brakes on the motor or car “chugs intermittently. More of a jerk against the brakes.Not all the time however. Mostly when warm. Although it was -12 deg f and I did it then too. It’s like a single cyl misfire. So far no codes no check engine light.
It’s not a constant miss just intermittently when stopped with the brakes on. It seems to go away as some as brakes are released. Does not make any difference how hard brakes ar on. I also tested as very low speed and gently pressed the brakes. I couldn’t feel it or hear it. So I’m not sure if it’s just something caused by brake actuation or something else.

Possibly something going on with idle air control.from the looks of it this was not serviced by the first guy.although he must have removed it when swapping intakes.. the Opti is completely sealed and new vacuum lines installed. Brand new water pump. No leaks.new plug wires and plugs.it may be the AC compressor cycling but it’s very quick what ever it is. Possible momentary converter locking and unlocking.if you listen very carefully you can hear or slightly feel the down shifts when coming to a stop. Doesn’t seem be associated with these. To me it seams something associated with brake activation.

[vilefly]

We need to know what the IAC count is on a warmed up engine in Park and then in Drive. Should be 18-23 idling in Park, and about 24-30 in Drive, no climate controls turned on.

Then we can go on to see what condition the transmission fluid is in. Red with clutch dust, brown with clutch dust, black and burned? The smell of the fluid is important. If the IAC counts are nominal, then I wonder about the TCC solenoid sticking a bit. I have had to drive cars for about 20-30min above 50mph on the highway for this type of symptom to show up. Sometimes it is bad enough to stop the motor once, only to let the car restart with no idling syptoms. Clutch dust in the fluid usually is the cause....fluid change and filter will solve the sticking solenoid issue. It feels like someone driving a stick shift forgetting to disengage the clutch while hitting the brakes and killing the engine as a result. You symptom is milder, I think. Near-stall.