Chevrolet Monza turns off when brake and clutch

Hello and thanks beforehand for reading my concerns about my problem.
First of all I have a Chevrolet Monza Sle/E 1993 with which I had no problem until I had to take him to technical review where he was rejected by gases. Therefore, they changed the oxygen sensor, but before that the mechanic walked without him with the hole uncovered for about 10 minutes in which the first 5 walked without any problem only the annoying sound. But then every time a change was lowered the rpm went down loudly but without arriving, which began the problem that I have today after the oxygen sensor has changed the rpm did not stabilize and in any traffic light it went out but only in relief since in speed no problem and all this takes it to another mechanic which verifies the hoses to the empty sensors and nothing then told me that it could be I distrust the butterfly position, which gave it an opening margin which resulted and the RPM stabilized more than before now it only varies between (980 to 1000 rpm) compared to before (1050 to 1250 RMP) but I still have the problem that in speed if I press the clutch or clutch and the brake the car the car It's only sometimes but on the road it is more frequent so I would appreciate your help very much

Check out the ground cables and clean them and check that the cables do not have internal sulfate

You can have a problem on a brake empty (hose-valve-serve) the air that enters varies mix (for motor)

First of all, thanks for answering,
what place are they?

Thank you for responding,
the hose that goes from the servo brake to the TBI has been reviewed and this ok
another symptom is that in the morning it goes out alone, since it cannot keep the rpm and the solution is to keep it accelerated and put the vehicle in motion so that the rpm are stabilized