pav

I've had diagnostics run on my car and no faults came up. I've changed MAF sensor and still the same. Doesn't happen very often either

Recently my car mpg dropped a lot. Havent changed driving style at all. Tyre pressures are as always. It's an audi A4 avant 2.0 diesel 147bhp. I use to get around 48-51mpg on motorway runs and around 30mpg in town. That dropped to about 42mpg on motorway and below 20mpg in town. Also car doesn't seem as responsive as before. Any help would be appreciated. Thank you