I have a 89 rx and hava a problem with it. I will start up fine and run normal up to 3800 rpm. but then after that it will not go any faster, I looked online and 3 people said that it is a bad ground to the ecu but I fixed that and still does the same thing. if I could have your input on this that would be great. thank you

 

Your secondary injectors may not be operating. Check for obvious things first like damage in the engine harness, fuel pressure, and so on.