Two problems!!! help needed for father in law!!!!

[C8 CDS]

Hi, I am normally on the Cerbera forum, but my father in law has a Chimaera 4.0litre '96 year, and is having a couple of probs with it. So he has asked me if i could post a thread for him, in the hope i can get some answers!!!
Ok then, firstly he is having problems as to when he is cruising along at a constant speed, this could be at 30mph or 40 mph etc, but his chimaera seems to be 'surging' - so feels as if it is slowing down then speeding up...any ideas?? He had done all the usual things that most mechanically minded and handed people would do, changed plugs, leads, filters, fuel cleaner added etc, but nothing seems to stop it happening??? Odd!!
Secondly, he has just sprung a water leak!!! it is coming from the front of the block, He has checked the water pump and has nothing coming out of it anywhere, it is worse when the heater is on, and almost stops when the heater is off, any ideas????
Thanks

[bigdods]

What gear is he in when its surging ? If I tried to drive my chim at 30 in 4th (for example) it would surge all over the place. My general rule is if its below 2k revs then its time to change down a gear. The surge and snatch at low RPM can be fixed IIRC by upgrading to a 'proper' ECU or by having a remap.

[Don1]

I have the same issue at 3k rpm - it's the time when the map changes to open (IIRC) - hence the surge.

[pilgrim13]

I had the "surging" problem I think you are describing, at constant throttle you could feel the engine holding back slightly for about a second then it would run ok for a second then hold back for a second etc etc etc etc. I took it to David Batty for this and other things and it was cured by adjusting the ignition timing.