Message problem "Selector 4 Service"

Hello good day everyone waiting for them to find great coordial greetings.

Well once again I turn to you to support me since the following message came out, "Selector 4 Service" I tell you that my truck is a Jeep Gran Cherokee 1997 limit 4 x 2 6 cylinders, it has as a 1 month that this message came out and two weeks ago I get in the next fault, walking the repeating truck does not accelerate as if the accelerator is disconnected, you will not pull it You carry and repeat again without any problem, now I manage that but I have to turn it off to accelerate again, the mechanic told me that the crankshaft position sensor, since it did that to me being in my daughter's school and move the sensor and the truck stabilized, since I found that when it slows it as it loses pressure as if it wanted to go out, it I moved the crankshaft sensor and the truck on the way as if nothing told me that I was wrong, and 4 days and today in the morning I spend the same thing you accelerate at 90 km and repeated the accelerator no longer answers you have to save you to take the truck and turn on again and ready. Someone will know what I can do. thank you.

Well I have a similar experience with a Nissan Cabstar. You have to know if you have electronic accelerator that I suppose that if and if so check the connections and the potentiometer because in my case I was doing the same thing I was walking and suddenly I was left without accelerator took the contact and put it again and worked and reviewed it and they were the connections that were loosening to see if they were.