sounds like stuffed pressure regulator

You shouldn't need to do anything about the idle - they have a bypass system with a seperate idle valve, that feeds air into the manifold to maintain it's idle speed. The valve is mounted on a bracket near the coil, and has 2 large-ish vacuum hoses, plus wires going to it. One vac hose goes to the manifold, the other goes onto a port in the plastic inlet duct.

If you don't have this setup, then it will stall, but it shouldn't cause the surging.

Thanks Hainzy, yeah I allowed a week for this to be done, its my daughters car and she has just got her "P's" and I said I would knock it over in a week while she had some time off from Uni. Since then she got herself a part time job...car not running. The doner car had a recoed engine in it as did hers so I decided to swap heads, good choice as her heads was not that crash hot but the EFI one has harden seats fitted, small yay, so lapped valves and done stem seals as well and Fitted all new gaskets. Then the fun began, lots of little annoying s*** things, Alternator didn't fit using the blue mounting bracket off the thermostat housing, so remove one from VK, clean, cut off power steering bracket, paint, fit. Fit fan belt VH 900 to short, VK 940 to short but forced it on temporarily till I figure out what will fit! Fit Idle valve mmmm fuel regulator does not fit as VH heater hoses are different, cant fit VK hoses as original power steering pump is in the road, so relocate regulator to wheel arch. Wiring in computer is normally straight forward except someone had hacked the loom and added different coloured wires to the originals, IE reds to blacks, so stripped the loom down. Changed fuel lines from front to back and swore at the tiny cap between the rack and body work! Removed EFI tank, removed objects inside the tank, only to find out that the cork gasket for the sender unit is obsolete ! So make up new gasket, swap tanks, fill with fuel to find there is a hair line crack in the tank at the return pipe ! drain, remove, replace with a VL tank. In between all this I got called away to load a truck (lost a day) and do night shift (slept a day). Went to fit accelerator cable, master cylinder was in the way, so swapped brake boosters, fat one for thin one, only to find there is a difference in the master cylinder as well ! So swap them and bleed brakes. Finally car starts , runs, idles, rev's, yay ! Then take it for a drive as mentioned above.............. the rest is history as they say. Now so far changed fuel pump, fuel regulator, no start, next is idle valve, from there we go back to the beginning again !

Yes HK brand new cam and lifters went in when i had the motor stripped down. I have traced the problem back to "no spark" ! Why no spark I dont know yet.....has new coil in it now so its either in the dizzy or Im loosing power in the start position.......tomorrow is another day

Yes new HEI coil today no luck so up for a new module for the dizzy tomorrow wonder what thats going to cost me lol

Still fighting with the bloody thing, changed every thing that is humanly possible- computer- fuel pump- all fuel regulators- dizzy- coil- air by pass- leads- cap- button- throttle position- relay- so on and so on. So now Im going to replace the wiring loom as this is the only other thing I can think off that may be causing the problem, as I mentioned before it was a bit if-ie as it had been used in another project and has extra wiring attached. So may be there is a break or poor connection in the loom some where............... Im annoyed as I have done this conversion before with out all this drama !

the injectors have wires running to each one, done in 2 sets of 3 wires, then to the harness where it runs alonside the intake runners. where each set joins the harness it is soldered. I found the soldering on mine was pretty crappy so resoldered them. but mine never had your symptoms so never replied to your post. sorry.