Puzzle with engine and speedometer pulls

Hi there.
I have a 2003 Kangoo. Let's see if someone can give me some idea of ​​what happens.

Before I start, I place the context because it is important for my story: I live in the Pyrenees, 1600m high. I routinely move between 1200m and 1700m. Sporadically between 700 to 1000m high and very sporadically at sea level.

First symptom: intermittent speed jam. When that happens, the engine gives light pulls, especially in marches 1, 2nd and 3rd. Unstable slowed. When the speedometer works again, the engine goes fine as a silk. It looks like an electrical failure.

Second symptom: I go to areas at 700m high and, this time, with the speedometer running, the engine pulls reappear. To all that, the intermittent needle failure persists and I begin to doubt. I realize that when I exceed 1,000m high, if the speedometer works, it walks again with total fineness. I think it is a coincidence.

THIRD SYMPTOM: We spent the weekend at sea level. With the speedometer running, the pulls and the unstable slowdown are unusual. The van becomes almost inconducible. I realize that when the needle falls (because the speedometer continues to fail at times), the pulls follow but less violent, the uncomfortable driving being but much less than when the needle marks speed.

Fourth Symptom: Touch Return. 230km where we pass from dimension 0 to 1600. While the needle marks speed, the engine pull is a true ordeal. I think that at any time the car is going to stop. "Fortunately," the intermittent breast of the speedometer makes when the needle falls, the pulls decrease and in 4th and 5th I can advance with relative stability. I pray so that the thing does not go anymore and to get home to be able to call the mechanic tomorrow.

Fifth symptom (which makes me hallucinate in colors): again from 1,000m high, when the speedometer works, the injection is stabilized again and the van is fine as if nothing. They follow the flashing falls that cause pulls in short marches, but compared to the other it doesn't seem so much.

I don't understand anything. The failure at different heights is more than proven. But I don't live in Bolivia 4000m high !!

I understand that I have a minimum of 2 breakdowns:
1- The intermittent speed of the speedometer that causes engine pulls.
2- The engine pulls still with the speedometer running but at sea level and is solved only from 1000m high.
Will everything be related to the same? Any idea ?? : Cry:

Thank you and greetings.