Help ive spent a fortune

[djrooni]

i bought my 1999 vreg 528i touring a few years ago, and a year later, developed problems, starting with overheating...a visit to the garage suggested that the head had gone,i had it replaced, still not right and having begun my spending it was determind that it had a crack in its bottom end....bought an engine for it that had 30k on the clock, had it fitted, cost a stack, worked ok but not spot on, went back, needed new camshaft sensor and was ok for a while, then the little symbol shaped like an engine came on!back to the garage they plugged it in they said lambersensors! driving ok and no more £ i left it and its been fine, then 2 weeks ago, drove it a bit hard and she was running great, got up the next day to go to the shop and the eml and traction control light was on and it went into limp mode, trickled it down the garage plugged it in said throttle sensor!they reset it and it drove fine, i used her no probs ,later drove 35miles fine,went fishing got back in her in the early hours to go home and the eml and traction light were back on!limp mode, mate phoned rac whilst i tried an old trick of turning ignition off locking and restarting, it didnt work again and again i tried and after about 20 attempts the lights went out and she drove fine so i cancelled the rac, 5miles later eml traction and limp mode!drove back at 55miles an hour,dropped my mate off, got back in car started her up, the lights were out and she ran fine, home next morning got up to check her and she was fine, but i rang the garage to get it checked, they said theyd pick her up and when they did she was in limp mode eml and trac again!10miles an hour to the garage plugged her in, said throttle sensor!reset it they kept her for the day, tried her all day no problems gave her back, i went shopping saturday drove fine, went to come home and was in limp eml trac again,drove 1 mile pulled over lock unlock lock unlock tried to start and was fine,drove home,jumped in today to take my daughter to work guess what....yup,eml limp traction control! im nervous to use it, cant spend much more on her, and certainly cant change her unfortunately,should i change the throttle sensor?could i do it my self? please help