81 GLi running problems after being stored

This is probably a bit unneccesary, but i'm intreiged. I've just properly started work on recommisioning an 81 GLi cabby (currently stripping to do the welding) so i have a few questions, the car has been off the road since 2006 and sat on flats unstarted for about 4 years in a garage. I havn't got the time or space (car is living outside) to do a full resto, so its a case of sorting the bodywork so its solid, the dash is coming out to remove a dodgy old alarm and then fully service the mechanicals

The car runs, however touching the accelerator will usually make it splutter and stall, it will be getting a full service once the body work is solid consisting of:

-cam belt
-auxilery drive belt
-plugs
-leads
-dizzy cap and arm
-water pump
-coolant flush and change
-oil change
-gearbox oil change
-air filter
-coolant hoses
-fuel filter

Plus the brakes overhauled etc.

It seemed a bit better when i changed the old fuel for fresh, and its much better when its warm. My question is what would cause it to splutter and stall when the accelerator is touched? If i slowly press the accelerator it will sometimes pick up, but usually all of a sudden the revs will jump to that speed. Currently the rev counters not working, but when the revs go up the needle will sometimes jump up. Also its not currently charging, and there was talk from the previous owner about the water pump not pumping. I am yet to check this though, just remove the top return to the expansion tank and see if some comes out?
Its stored at the side of the house (with about 12 inches to spare between both sides) and brought down onto the drive every evening to work on, this running problems starting to annoy me! I know it needs a full service before any real problem solving, i want to clean and paint the engine during the service when the alternator, water pump etc is off. And it seems stupid to do all that when the biggest job of sorting rusty bodywork is yet to be done.

Also, the car has its original 1.6 injected lump, does anyone know the engine code? The label in the boot is faded and the owners manual missing. Its fitted with an oem oil cooler which all looks original. Someone suggested to me that its the early GTi lump being used up by vw? The reg is BGJ479X

Thanks chaps 

its probably the EG code engine same as a mk1 GTI, if the sticker is still readable in the boot it'll tell you

as for fueling issue i would give the tank and fuel pump filters an inspection plus do the usual filler neck rot and tank debris checks. take the filler neck off if you can as rot often hides right where you cant see. plsu while its off you can buff it all back to clean metal all over and give it a spray of etch primer and good underbody paint. these days peeps like to use epoxy based for chassis bits

Engine code is also on the engine block just below spark plug No.3.

forgot the handy link!
http://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=how-to_2%2Ffuel-tank-cleaning_3