Hi guys. Had Octavia auto tdi 90hp for about two weeks. In the Morning and the Beginning of a journey from cold. Car seems Fine. When ive driven about 7-8 Miles in Normal a-road traffic and the engine is up to temp. Just starts feeling a big gutless. Doesn't like getting up to speed the way it would when cold.

 

 I've Ordered a new Maf sensor. Ive cleaned the sensor with ipa but nothing changed. Also it makes no difference unplugging. Its got five pin socket with 4 connections in the sockets. Not five?  I noticed that when cleaning the sensor that there are two metal pieces on it that dont have no component attached. There is however on the moulding, a picture of one.   Thinking i may well get a n75 too. At least i can eliminate them if nothing else.  Ive heard a zener diode across Pin 4 and 5? 

 

 a few other things ive noticed when under the bonnet are that the air filter housing is a little loose. the intake that does to the body work right next to it isn't bolted in place. all the pipes seems in order. There is one.. quite a large one that goes along the front of the engine by the radiator.  seems to have an outlet near the left hand side that isn't connected to anything? 

 

 Forgive my lack of knowledge. 

Get the codes read first with vcds. You’ll probably get an over boost fault code, which in these cars is sticking vanes in the turbo. If you use this link it will explain how to remedy this. 
https://www.briskoda.net/forums/topic/243533-the-mr-muscle-vnt-turbo-treatment-thought-we-needed-a-guide-of-sorts/?tab=comments#comment-2858744

It’s a very common issue with these vnt turbos, caused by carbon build up from the egr system. 
Hope this helps?

These cars are very reliable. You need to ask yourself what has changed. Just check that whoever changed the air filter at the last service properly replaced the electric connection that goes to the large pipe which feeds from the air filter and that is in the way of a filter change. If that plug connection doesnt sit right your TDI will be sluggish and wont go over 70mph.  Unplugging obviously wont make any difference to the problem. Limp mode is a different story. That really is 15mph and the most prevalent cause is water in the electronic accelerator pedal. Back breaker of a job but WD40 will save the day. The water gets in from the bulkhead when its full of leaves and has blocked the drain holes.