I would be shocked to find a governer on a truck that old. Here is my theory.
I have owned a Cali car once. It was a 2.8L V-6 Chevy Citation. I loved that car and it definitely was a lot of fun to drive. It could beat a 305 powered Trans Am without a problem.
The problem I had was all of the Cali emission junk on it. The heating plate under the carb, the freakin 100+ dollar O2 sensor, etc.
So my first thought is......what's the cat like on your truck? I am thinking that it sounds like maybe a restriction in the exhaust. Have you checked the codes on the engine? Any sensor that is perhaps acting up on it?
Like I said, I don't know much about governers, I just find it hard to believe that your truck has one. I would start leaning towards exhaust restriction or faulty emission control devices.
Just me though.
