51 plate octavia 1.6 petrol problems

A friend has asked me to try and get some information for him regarding problems with his car...

firstly when you start it the engine seems to rev up and then down and up again before settling after pulling away.

fuel economy seems to have dropped down.

theres a rattle underneath.

now i am going to take the maf off and give that a clean with electrical cleaner but wondering what else i should look at.

its been on a scanner and throws up the following.

p0172 - fuel trim - system rich bank 1

p0300 - random misfire detected - any cylinder

p1141 - load calculation cross check

so anyway going to have a look at site for info on maf and location etc and would welcome any other assistance regarding this.

thanks

edit - I do apologise, first post and its the wrong section.

Edited 14 December, 201114 yr by thinisaz