I have a 173 in a Land Rover, not a "Holden" but getting help on old Holdens is not easy (I did own a HR in before the Land Rover).
The engine "is" in good condition and well looked after, regular oil changes and kept tuned.
I rebuilt the engine about 80,000 miles ago, had it balanced, fitted a Donaldson style air filter and oil cooler.
My question, just recently I replaced a couple of noisy lifters and since (it also appears to be getting worse) then when the engine is revved the lifters/lifter pumps up, most noticeable at idle, after a while (10 - 20 seconds) the engine settles down to a smooth idle.
During rough idle I pulled of spark plug lead to see which lifters were pumping up, determined that number 2 cylinder was the worst. Change the lifters with genuine parts, and the problem was worse.
When driving at a constant speed the engine runs fine, only stop/start driving is affected and getting to be come un-driveable.
The engine will still rev smoothly to 4500 rpm.
Any help greatly appreciated.