Car cannot go past 74~76 MPH

[slow2401989]

Hello I have weird one that I cannot figure it out, it seems to all be related. I have a 89 240 coupe the motor is stock, MT with roughly 143K on it that I purchased for $400.00 and is in need of some TLC. The car runs and drives as long as you stay below 4K rpm, the speedometer does not work nor does it show 0. When the cars reaches 4K it seems to bog down like when you let your foot off the gas, I am able push in the clutch and release and the car continues to speed up and does not bog down until 4K.Max speed is 74~76 mph based on my phone. When I turn on the head lights the gauge cluster light does not light up. Only a couple of times while driving at night the cluster lights come on, the speedometer works along with HUD and i can rev past 4K and drive faster than 75ish . Any ideas, I am guessing some type of wiring problem.

[LayNLow]

Check the 4th and 5th gear sensor wiring, they both limit RPM as a way of limiting speed.

[slow2401989]

Perfect thank you, i will check that.

[slow2401989]

I checked both of the sensors visually along with the wiring, but the car also does it in third gear as well.

[Datsun freak]

Sounds like a bad mass air flow wiring or sensor itself, check and trace wires from air flow sensor, check the tps and water temp also . Look for damage or areas that have been previously worked on Bundle of tape zip ties ect