P0299 fault and more

I drive a 08 Octavia VRS, I changed the timing belt last July and a week later the glow light started to flash now and again when I went over 2000rpm. I ran a diagnostic check and it came up with a speed sensor fault but I didn't get anything done to the car. Then about two weeks ago the car just lost it's power, when this happened the glow light would come on flashing and the car would go into limp mode. I got another diagnostic done and here is what the mechanic thinks:the fault reading is P0299. the turbo boost is less than requested however this can be caused by many things up to and including a faulty turbo. The air flow meter readings are low but they also correspond to the low turbo pressure,its debateable which is causing the other to be low.I wouldnt replace the MAF just yet. One of the causes of low turbo pressure is a leak on turbo pipes/intercooler but since the air flow in corresponds to the boost pressure I think we can rule this out.

Any ideas on what is going on? Is it a dirty sensor?? Faulty air mass meter, leaking hose?? Any help would be great