Looking for any advice please....

[Jasper26]

I have the 140 celica and it developed the famous bottom end issue so I bought a donor car. The engine in the donor car was perfect with no faults or lights on etc etc. I have dropped that engine into my celica now but am suffering with a problem. I got everything wired up all sensors plugged in all hoses connected as far as I can see. I used the ecu from my previous engine hopefully this is ok I also used the wiring loom from the previous engine. I started the car today and it starts after a few turn overs when it used to start first turn of the key. it is revving by itself very high and my exhaust is popping like to much fuel is been used. Also smells very fuely. When the car starts it jumps to about 3 thousand revs then idles off at 1 thousand for about 10 seconds then jumps back up to 3 thousand where it stays until I switch the car off. I'm also getting the following 2 codes p1656 and p0340. I'm hoping I've connected everything up properly. Before engine went in I had all gaskets replaced and had head skimmed so all that is perfect and as I say the engine was running spot on before it went in the car so it's definitely something I've done wrong. All help is very much appreciated. I will also state I disconnected the throttle cable to make sure it weren't that but it has no effect whatsoever. I'm praying it's a sensor or hose I've onnected wrong.