Impossible increase rpm when I press the gas pedal.

Hello friends.
How are you?.
I have a strange problem in my Micra 1.0 93'. Maybe I produce the fail by myself.
I can engine well the motor always in cold or in hot, but if I press the gas pedal smoothly the motor accelerates right until an amount of rpm. ( I don't know, because I haven't a rpm counter) and the motor goes down and up accelerating and decelerating all the time, although I keep the gas pedal in the same position, if I release it, the rpm are stable and the noise of the motor is smooth as usual. The engine start is right and quick and the noise right.

I explain in detail: It was broken a short water pipe "U" type during driving the car and the temperature increases near red mark, but rapidly we stop the car where we could.
The pipe that we found broken is the located under the: "delco" name used in Spanish as: High Voltage distributor (Where are plugged the Cables for the sparks. So I replaced this one and I refilled the circuit with coolant Water directly in the radiator after motor cold.
After that I was checking what produced the broken pipe and I decided to check the Thermo switch, fan motor operation, thermo valve and so on, and I decided to disconnect the Thermo sensor and I engined the motor again, but the noise was so rough and it was trying to stall the motor, but accelerating a little bit I got keep the constant slow motion rpm. Of course at disconnect the thermo sensor, the heat fan motor was working fine and then I switched off ignition key and reconnected the thermal sensor again. I have to say that this car had light on the Yellow lamp (CHECK) from 1 week before this problem until that moment, but the car was running fine without problems.

After reconnect the thermal sensor, the (CHECK yellow lamp) lighted to Off and I engined start again and seemed to be everything fine again: No lamps On in the panel and I tried to drive the car with all the coolant circuit full and checked and in 5meters running I could see something strange in the car: a strange noise during acceleration: increasing rpm and decreasing while the gas pedal is pressed at a certain point, that may be belongs to 1000rpm more or less, I'm not sure…If I release the noise is god and seems the stall is perfect.

Do you know if now the car is under "protection mode"?. The car was running fine before this problem.
Maybe I need clear any memorized alarm although there are not alarm lamps ON.
I'm thinking to check the throttle valve and recheck the internal connections and re-soldering as you explain very well in your pdf, but it's so strange that now I have a new problem. I don't believe it!.

After some test I could seen the 4 sparks dirty and the exhaust pipe was dirty as badly burnt petrol, when 1 week before this problem were right.

Im trying to get a Diagnosis device OBD1 by Ebay website with cables and CD that it cost around 25€-35€, but I don't know if have a good software for diagnosis and of course for clear errors.

What do you think?.
I would very appreciate your help.

Thank you very much for your patience.

Gerard.