Intermittent Jolt at speed

[LovingIT]

morning, I'd be interested to hear some opinions of what the following problem could be and how to troubleshoot it.

Its a mid 2001, 1.8 with 115,000miles

Challenge No. 1

When driving at 70+ mph there is an occasional jolt. Its over in split second but feels like the engine has lost power and is a bit unnerving! The jolt is intermittent, but occurs more frequently at constant motorway speeds, as I'm typing this I'm thinking that it may be something to do with the ignition, HT leads, Coil Packs etc. On visual inspection they look ok.

the engine mgmt light has not come on yet and it should do if there is a misfire...is this correct?

What approach would people have to troubleshoot this, I'm due to tow a caravan in the next few weeks so am keen to get it running smoothly - is it a matter of swapping components ££££!

Challenge No. 2

The car does have another issue which will get fixed this week - the IRD bracket has failed (vibration at 4000rpm) so this will get replaced (less than £15) but the LR article also says that the Mass Damper assembly needs replacing this is £75! What do people think about replacing this component is it worth the risk not to?

I look forward to hearing from you

cheers

[LovingIT]

answer to Challenge No.2 - replaced IRD Bracket (along with new bolt) and engine is now vibration free at 4000rpm - have not bought Mass Damper and will see what happens.

Challenge No.1 - am replacing HT leads and coil packs in un-co-ordinated approach as am running out of time before our Holiday begins! Will also look to replace the fuel filter as this is needed at 120k anyway

all comments welcome!