Toyota Celica 7 VVTI 190 , P0171(too lean) and B0101(speed clock died intermittently) codes , pls help new purchase

Description below. pls help as I just bought this car.

Something interesting about the CEL, I think this info may help isolate the problem

• It looks like the MAF may be new, but I will confirm that on weekend, looks like previous buyer found this problem and went for MAF originally, maybe he found something worse and traded in?

• CEL goes off when you turn the car off and may not come back on for a week or two if i drive slowly enough and with low enough revs, something is surely triggering this?? so I am going to trigger it whilst my friend is filming the dash on the weekend as its hard to keep eyes on road/dash at same time.

• Once or twice i seen it go on at lower speeds, I am pretty sure one time I was going up a hill, and another time I had something about 20 Kilos in the back I was moving around

It was quite a large item, a portable steel single bed I had in the back. I was only rolling along and the light came on 😮 what does this mean??