Bad running engine

Hi there,

4.6 HSE 1999 with bosch motronic with engine problem.
Faultmate ODB P0172 and P0175 say both cilinder banks lean mixture.
Also misfire at specially at nr 7, have change HT lead and plugs, no result.
Engine hesitates during acceleration.
I guess the misfire is a result of the lean mixture.
On petrol less misfire then at LPG.
It's not every day very bad, cold weather and cold engine is worse.
Something to do with an airleak after MAF sensor? , broken inlet manifold ?

Allyv8?

Regards,

Klaas