Change my 2005 vw polo engine now it idles but do not rev up

very limited info generic answer did you do a relearn for the throttle body ---scan for trouble codes

im also havin a problm with 99 polo 1.6 it revs high low high low and if da tank is below 1/4 it dies of while driving iv changed tank unit,trottle body, sensor nd after i changd tank unit da foat reads opsite way sum1 plz help me

First- lets change engine coolant sensor/ECT/ and you will be very surprised.Black head with four pins.Be very carefull when change it because there is pressure into coolant system.First-open slowly the cap of engine coolant tank.Then tighten again to safe coolant.Unplug the sensor,remove the pin and pull out the sensor.If the "O"ring/old one/ is still inside-take it out.

You need to check the cable the runs from the gas pedal to the engine, it might be rusty and need some drops of penetrating oil at the point it meets with the engine accelerator valve.

check the idle controll sensor.its stopping u from idleing when u let youre fooy off of the pedal.

There are many number of reasons for this problem...but a VERY common one is a faulty thermo sensor which controls air / fuel ratio.
John

the cover just pulls off and disconnect breather hose as u lift it.there is about 15 screws to remove then the cover opens

i had same prob. Sorry but im a noob when it comes to car stuff. I think its called the airflow, it just needs cleaning cost me £25 for him to clean it, piece of ****. Hope this helps.

100% sure it shows one of your cylinder compression is weak, please do a compression test to isolate the problem and get the head/pistons checked . This is a known problem with VW/Skoda 1.2 3 cylinder mills..

Hi, I have a 2001 polo 1.4 mpi it lackes power when you hit a hill it just dies, It has had new cat, fuel filter, fuel pump and throttle body, but is still the same it just dose not want to give me full rev's?