High RPM's low acceleration

My problem is when I accelerate on level ground, up hill, from lights the rpm's hold up to 2500 to 3000. Only way to gain more speed is to let go off accelerator and then re push accelerator to gain more speed, but rpm's go straight to 2500 and 3000 and slowly get up to speed sometimes revs goes over 3000 when only at forty km's sometimes even 20 km's. It is like I am forced to let go off accelerator as car is straining rpm's do not freely rev up and down more so get stuck at high revs and low acceleration car will lose power going up hill sometimes only going twenty km's up a hill with revs of 2500 to 3000 revs. Car revs high when taking of from stop position when I need to take off faster from lights so it takes a while to gradually gain speed whilst constantly letting go of accelerator and re pushing it to gain higher speed, when car is at speeds of sixty going on seventy or eighty even hundred it stays on 2500 but sounds like it is not meant to so every now and then I have to drop speed a little in case it is revving too high for long periods of time.I have changed fuel filter 02 sensor, timing belt, air filter, thermostat and thermostat gasket, power steering belt, spark plugs, and leads, oil filter, water pump. I have had a transmission service a general yearly service. I have put fuel injector cleaner through. I have sprayed carburetor cleaner through the solenoid hose. I have done diagnostic test checked for any leaks in hoses or worn hoses. I have recently noticed a very potent sweet smell coming out of exhaust when car is running or just started not sure what that is either the transmission service that I had done was a flush. I have also noticed a bit of yellow on one of the spark plugs although they were brand new not sure if it has anything to do with it. I do not know what else to look at other then the solenoid valves head gasket ECU sensor. Can anyone help me as I am just really stuck and I been researching and changing stuff on the car for about two months now, spent so much money. Thanks in advance.