GTI Starting / Running probs

hi new member today after buying a mk1 gti cabriolet but it has a couple of probs (at the moment) the 1st is struggleing to start in the morning and the 2nd is when it is warm and after running it for a few miles it starts jumping and jolting and loses power but if i stop turn the ignition off then on again its ok for another few miles then it starts all over again can anyone advise me before i spend money on wrong things or get ripped off  THANKS

Get a full service carried out , check fuel tank for rust , search site for rusty fuel filler and tank cleaning .

Cheers………….

It sounds as if you could have fuel delivery problems which can be caused by any number of things. In addition to the traditional Scourge of the Rusted Filler Neck, there are a number of fuel delivery possibilities. They are:
Sticking fuel pump non-return valve.
Fuel pump relay on the way out.
Fuel pump on the way out.
Incorrect delivery pressures [metering head]
I have listed these in order of expense. The first three are simple jobs for the moderately mechanically capable. The metering head has a delivery pressure valve on the side & this can also be serviced by any competant amateur - beware of the shims under the spring! However, as far as dabbling with the metering head is concerned - forget it! Restrict your efforts in this area to checking the free-movement of the central plunger which is activated by the air-mass plate [aka The Frying Pan]
At a [genuine] mileage of around 150,000 these problems would not be unusual I hope that this is of some use

another possibility would be the fuel filter, easy and cheap to replace (if not already mentioned.. kind of skim read the posts)

THANKS TO ALL THE ADVISE I HAVE PUT A NEW FUEL FILLER NECK ON AND DONE A FULL SERVICE WHICH HELPED WITH THE STARTING PROBLEM BUT THE CAR STILL RUN BADLEY AFTER IT HAD WARMED UP SO I HAD A LITTLE PLAY UNDER THE BONNET WITH CONNECTERS ECT AND THEN AFTER MESSING WITH THE WARM UP REGULATOR IT SEEMS TO HAVE SOLVED THE PROBLEM(TOUCH WOOD)   THANKS FOR ALL THE ADVISE KEEP IT UP