I have a 1996 hb 4cyl 5speed It runs good then all of a sudden it starts acting up. I mean it will not rev over 2400 rpms it will idle maybe stumble a little. You can still drive if you keep it under 2400 rpms also if you are going down road over 2400 rpms when it is running good it may start doing it to. I slow down and can a least go 55. It is driving me nuts . Any help would be great.