6th gear shakes ?

[A26B]

Originally Posted by onetinsoldier

Well spark isn't an issue ! I did change the O2 sensors which made somewhat of a difference .Now only #8 seems to foul -sooty . I'm wondering if the injectors need cleaning , the car is only driven a few times a year ?

the car is only driven a few times a year ?

Is the fuel fresh or treated with fuel stabilizer?
Do you keep the fuel tank full when not being driven?

I'm wondering if the injectors need cleaning

Understand you have a 1991 ZR-1. Original 89~92 model ZR-1 injectors are venerable to damage from gasoline/ethanol blended fuel. Unless you use only 100% gasoline (no ethanol), it is likely that your problem is fuel injector related. Cleaning the injectors will not remedy injectors damaged by ethanol.

Now only #8 seems to foul -sooty

The correct fix is to replace all 16 injectors with modern injectors manufactured with components that are compatible with ethanol.