not a mopar but a vintage car !!! need your advice guys !

i have a 1989 volvo 760 turbo sedans with a 2.3..and i have a problem with my iddle , when i start it , it goes crazy between 1000 to 2000 rpm and after few seconds it returns normal , it did that for the last 6 months but yesterday i went out and ..guess what it didnt want to stop after 10 minutes ! moved for few seconds but was reving by itself from 1 to 2000 rpm was like driving a supercharged bick block ! , but i parked right away felt that it was really bad for the kickdown....transmission and motor ..dont want to break something .. so every garage tells me that they dont have a scanner to read the 1989 volvos.....theres some odb1 and obd2 things that i dont know well so what can i do now change all the little parts that i think it is ?? oxygen sensor , isc valve , mass air flow sensor etc... selling the car to my bestfriend and its completly non driveable ..

have any idea ?