99 c250 lack of boost at high speed

[Ad777]

Hi all, yet another question. The car seems to pick up fine when driving around country roads but just came down the motorway for the first time was sitting at 70 , started going up a hill and started dropping speed,kicked down,dropped a gear but didn't really pick up, sat round about 60 till top of the hill. There is a crack in my rubber end of inlet manifold which I am waiting for a replacement for...could that cause this? Any other pipes to look at! Fuel filter was changed recently. Advice appreciated as ever! Adam

 

[LostKiwi]

Yes it could.

 

[Ad777]

Thank you.