Motor vibration in D (Drive) being at a high

Greetings, I have a problem with a 2001 automatic neon, the engine vibrates in a high while in D (drive), when you pass to neutral (n) it feels a little less but when I use the reverse it feels more and worse when the weather turns on, apart, the engine feels slowly you have to plunge the accelerator no longer responds to me very well.
I already made these changes:

spark plug cable
tuning 2 motor supports, lower right and the superior

I hope someone can guide me, because the car does not send me any \ "Check Engine \"

Vibrates as if he wanted to turn off, if so checks the Relay regulator, in general in all vehicles it gives problem, but it is more notorious in the automatic, the chek does not turn on because this is an actuator and not a sensor, they can be cleaned according to it is the one you possess, but if the fault is only in Relay, and you already changed the things, I recommend that you check it that you check it. Relay always, that is, regular it from the accelerator piola are very accelerated and spend more fuel.

If the engine vibrates as if you wanted to turn off, when I reach a high vibrate engine and I have to change neutral to normalize its rhythm, in prolonged ups rpm fall and have to accelerate to normalize the RPM [as if the pump will not inject enough fuel] adjust !!! Do I have to concentrate on the speed box ???

Gracia Sde Nate Mao for his orientation and great greeting !!

I do not think it is from the speed box because you have mentioned that in the climbs the engine \ "is wrinkled \" and you have to accelerate a little more.

This symptom is of lack of fuel so you have to look at the fuel pressure regulator, gasoline filter, lambda probe, flowmeter or MAP sensor, (I don't know which of the two systems it carries). Another thing that may be giving problems is that you have some air leak, so that the engine reaches an air from the outside without going through the flowmeter, in this way, the switchboard does not detect the amount of real air that the engine aspires and is injecting less gasoline from the account.

All the best.

Thank you very much for the information ,,, !!! I will request the review that you mention and personally believe that if it is very likely that the failure is originated by any of the causes you indicate since the speed box would cause problems in the advance of the vehicle not of the engine ,, and this fault, it is evidently a problem in the supply of the fuel or the air or both !!!
I hope that the mechanical workshop soon fault the fault and I will inform you of the result !!!!

Thanks for the information since unfortunately the mechanical workshops make their own once the vehicle leaves them or sometimes they need user's guidance to address the failure and with this information I think we will save time and up to $$$$$ ,,,, thanks again !!!!