Last year my car ran fine (95 lt1 4l60e in a 87 firebird) since then I strocked it to a 12.5:1 383 with a direct port nitrous system. I got the computer set up for this configuration and now I get code 97 (4K pulses per mile fault) and the car will not rev above 5000 rpm, where it hits the rev limiter when the rev limiter should be much higher. The car runs fine around town shifting and everything until its wide open, could the computer be in limp mode due to code 97?

As I said last year the car ran fine and the speedo was not hooked up then and I did not get the code 97. Could this be in the computer program?

Since I got this code I also replaced the VSS but still I got the same code.

I am confussed, what could this be?

Without a data log, how can you be sure its a rev limiter?
You'll have to ask the guy that did your programming.

If the car ran fine and then started to "act funny", unless your ECM/PCM got a "virus", your problem is not with the ECM/PCM.

As that is a 4th Gen Engine, you may wish to go to a 4th Gen site to discuss the code. But, based on your discussion, the problem is either mechanical, electrical or some sensor. But not the ECM/PCM and definitely not the programming.

Unfortunately, as this is not a "DIY Prom" question, but more of a Tech/Gen question, I am going to re-direct this to Tech/Gen and maybe Vadar can help you.

But also consider posting on a 4th Gen site as well.