Liam 110889

Hi All, I wonder if someone can help. I have seen a few posts surrounding this issue but all seem to have warning lights etc. When driving my Lexus on a long journey it seems to go into 'Limp mode' when I come to a stop at a roundabout and try take off again. This happened this morning on the way to work when I was driving almost 2 hours at 70mph on the motorway. I came off the motorway and slowed down to a stop at a roundabout. When I went to go again in 1st gear the revs stuck at about 1200 no matter how far I pushed the accelerator. I have to pull over and turn off the car then back on again and it seems to be ok. This has happened a few times so I had it plugged in an no error codes were shown. I cleaned the MAF but doesn't seem to have made a difference. Is anyone able to help on this? Many Thanks Liam