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Pete, Technician
Category: Car
Satisfied Customers: 26731
Experience:  17 years automotive training and experience.
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Nissan xterra: Hi. I got a 2000 Nissan xterra. At 40 miles

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Hi. I got a 2000 Nissan xterra. At 40 miles an hour it start to run rough like it's missing
What can be the problem.
My name is XXXXX XXXXX I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would ask to see if you still need help with this.

From what you have described usually a misfire at higher speeds like this here can be a fault of spark or lack of fuel.With all of the components you have replaced here this may be a fault with the ignition coil assembly which is integrated into the distributor itself.The coil signal can break down under high rpm loads and cause this here.In some cases I have drove a vehicle with a timing light clamped onto a spark plug wire and ran up into the vehicle routing the wires carefully,then face the strobe light from the timing light down towards the floor so someone else can watch the flash of the light and drive the vehicle to see if when it acts up if the spark is cutting out.If spark is cutting out then this may be the component at fault.

The fuel pressure should be tested as well to see if it is dropping out at this speed,this would require a fuel pressure test gage and special adapters to do this.The fuel pressure should be right at or near 34 psi when this occurs,if it is lower then this then you may have a weak fuel pump causing this issue here and may need replaced.

Both of these here can cause this type of fault and need checked into to see if the fault can be located and then repaired.

I hope this has helped in some way here.If you need anything else don't hesitate to ask thats what I am here for.If you are not satisfied with my help here let me know before rating my help.

Thanks Pete
Pete and 3 other Car Specialists are ready to help you

I am following up with you to see if you still needed help with your question you had asked.If my help didn't satisfy your question please let me know so we can continue.

Thanks Pete