1983 GMC S15 brake booster

you mean the truck shakes when you com to a stop not in park. check rotors for warpage as that is probably why and check rear brakes as well.as far as being hard to stop it can be the booster or the check valve or not enough vacuum to run the booster.

No in park the truck shakes and the motor bogges down. Ist not the rotors. Tha brakes dont work good ,like it a air pocket but I have bled them. It is hard to push when in park and doesnt work proprely

They were working good then this. There is no vacume leak on the hoses ,I have bled the brakes, They are a little better since the paportion valve I put on but they are not working correcly .

if you are in park and applying the brakes thenit's a vacuum leak or and engine miss. have a local pro look at it

So ,with the truck in park and I step on the brake peddle an the truck missis , I nedd to get a fog test done on it?

no something is leaking vacuum it sounds like which could be the booster. you might hear a nhissing sound inside truck while brake is on....

I took the hose off on the booster and put my thumb on it an it seemed ok but when I put it back on the booster it did it. The brakes where a lil bette but felt a smige better. They dont slow you down like they are supose to they kinda slow you down then like release a little an then the peddle goes in an you can stop now but its not a nice stop.

you are to inconsistent with your question and what you are doing, have a local pro look at this as I do not know what you have done and want me to straighten it out for you. I have no further suggestions.

It is my booster (brake) from what we have gathered..

Sorry, Thank you..

You helped me solve a problem I thought was it but not sure. The Questions I ask were to help me and I am sorry it confused you. Thank you for you help .