Oldsmobile/Buick Repair: fuel, air plenum, varing

Question
my 92 la saber will omly run at full speed will not idel black smoke comes out of tail pipe in varing amounts thanks

Answer
Hi Henry,
I think that has a system on the injectors that I am not familiar with. Central port injection, I believe it is called, and uses plastic hoses inside the air plenum, I think.
The little I have seen about that system made me wonder if those lines ever break, and what happens.
I may be way out in left field, but I think that is what you will find.

Van