Pre heating warning light

[Uppa1994]

I have a y reg 1.4 clio and a few months ago the pre heating light came on, this limits the car to about 2 and a half rpm. I took it into a garage and so far the full exhaust has been replaced including both lambda sensors, they found that the car had 7.5 litres of oil in it, which blew the head gasket. So that got redone along with skimming the cylinders. So the engine is basically brand new. They are running out of ideas as to what the problem is. They have said it could be either the throttle control body or the ecu has a fault. Someone please help!! I am running out of money, and patience with my car and I just want it fixed