Please help

[carissa ford]

So brought my a4 1.8t avant 2001 the people who we brought it off had changed the engine and put an apu rather than an awt in, we didn't know this at the time and was fine when test driven, it was lumpy and horrible when first started, when driving engine management would flash on and throw it into limp mode, we discovered was wrong engine and figured could just be this as they are different, we have put an awt in and still lumpy when first start but not as bad but the revs do not stay same at idle goes up and down a lot, has been okay to drive so far but when put foot down (mainly up hill) you don't get the power should be seems to have a slight delay rest of time goes as it should. also failed on co2 emissions, it'll drop into green then the revs start going up and down and flys straight into red, codes are very intermitant weve been getting cam shaft position sensor, and misfires and fuel being too lean, starting to loose faith no one seems to know what it could be and have already spent a lot of money, have seen a few older posts on here about crankcase breather valve and prv we've changed them and made no difference cam shaft position sensor has been changed. The mot first time round were told it couldn't be the cat then this time they said it might be any ideas would be appreciated..to me it's got to be something that's still original as the engine has been changed. The car is clean otherwise ..trying to upload a pic but won't let me. Please someone help..thanks

 

[Sandra]

https://www.audi-sport.net/xf/threads/how-to-upload-pictures-to-the-forum.322378/