got a rough idle and when I try go maintain a steady speed it gets a little miss on 1991 Chevrolet S10 Blazer

I have replaced most vacuum lines but the line from the carb to the vapor canister when I take it off it does not change anything no difference?

It has throttle body fuel injection which the fuel mixture is controlled by a computer.
If I were to start shooting parts at this Blazer I would put a new O2 sensor in it.
If you don't want to guess, find somebody with a OBD I scanner software to look at the serial data. unfortunately that also means a PAT(PROFESSIONAL AUTO TECH) that can understand what the data means.
the only code that came up was map sensor and it all check out ok I replaced o2 sensor tody still the only thing I found puzzling was where they line from the fuel vapor canister goes into they intake on the carp body nothing change when I took it off to check it.
The purge system is fed at the throttle body. It goes from the throttle body to the purge control solenoid then to the canister.
If you had a scanner that will pull codes what did the serial data look like?
had the codes check and it read map sensor had it check and everything was fine. I'm thinking TBI cleaning and go from there thanks
That vehicle will provide more than just codes. What does the data stream look like.
I pulled the TBI off and cleaned it, was all clogged up seems to run good down, thank you