Recently my van motor seems to be loosing power, its seems to have started with a lag i.e. a few seconds after loading the motor it would pick up but now it really seems to be struggling, I guestimate approx 1/3 /1/4 power loss. It seems to still get there but acceleration is almost non existent and when put under load I can feel the motor is wobbling/vibrating a lot more than usual through the gearstick. Any ideas or similar experinces?

I'm hoping its not too terminal, its not burning oil a minor exhaust leak but no more than usual.

not that i'm an expert or anything, but ......
sounds like a loss of compression, so could be a valve issue, when one of my valve springs broke i had similar power loss/struggle, and engine vibration etc. (although that was sudden not gradual) might be worth whipping the heads off and just checking the valves though.

You wanna borrow my book again ?

First thing to do is give it a service. plugs points and valve gaps ect. no need to take the heads off use a compression tester for that.

Thanks folks, I'll do the service and I have a compression tester so I'll do that at the end.
P.S I may have finally secured a lock up, going to see tonight and discuss how much - will keep up posted.