after i got my long tubes installed(not coated), the car ran fine for a day or 2...then as soon as it reached operating temp. it died..untill it cooled down then start back up...changed out the icm(delco,from chevy dealer),msd coil it still would happen..ended up getting the car diagnosed codes that came up were 16,42,36 ..from searches i done on here it points to the opti or harness..got a new harness in today from casper..i was just wondering, would the car run different? sputter choke,if it was the opti? cause cold, it runs fine,pulls strong.does this sound like it would just be the harness?also when it dies, the rpm's start shooting up and down.
the cars a 94 lt1,boltons.
thanks for any help.

 

Sounds like what happened to me last time. The electronics in the optispark would get hot and quit working. had to replace the opti.

 

A jumping tach would be consistant with a faulty signal from the optical sensor in the Opti.

 

Forgot to mention mine did this as well.

 

by being consistant, does that mean..happens all the time, as far as regular driving also? cuase rpms only jump when the car shuts off..as far as regular driving, its fine..when it dies, thats when they jump.