ezS10V8

I had almost the same problem. Engine ran fine but at around 4k it would cut out, like I was hitting a rev limiter. Mild Build 350 with Accell HEI in cap super coil. I replaced the carb replaced the fuel filter full tune up replaced the alternator replaced the battery replaced the whole fuel tank Rewired the entire truck redid the entire fuel line layout ( nice electric pump, return line, and fuel pressure regulator ) after following tons and tons of advice threads. Was getting ready to give up entirely on the motor as the internet had convinced me it was a problem in the valve train and I had another 350 that was almost completely stock in the garage. I took the tach out of it to give to my stepfather because it wouldnt rev so I didnt see a point in having one installed. Soon as I unplugged the tach the motor wouldnt even idle, had to totally re-adjust the carb, after doing so, every time the engine fired the entire truck would reverb, she has no problems hitting redline instantly now while driving down the road. just like I wanted when I did the build. It's almost impossible to keep the tires from squealing if I have the wheel turned at all now and I can use the full tach range... all because I didnt think that a silly tach wire could cause all of this headache. My symptom was that really hard acceleration would make the engine act like it was hitting the rev limiter, and if you walked the accelerator it would cut out @ about 4000rpm. I was convinced forever it was fuel delivery because the RPM cutout wasnt always exact and it was a little eratic. A few days the engine ran fine, then back to nothing. Sitting in the driveway I could rap it out with no problem.