Not sure if this is in the right topic but... Got a 75 Spitfire 1500. Its always been reliable bit over the last year it's had a problem which is stopping me using it. It starts fine, then after around 10 miles (sometimes more, sometimes less) it starts juddering and losing power. This progressively get worse until the engine stalls. After a while it will start again, then the same thing happens. Eventually I can manage to limp home, although there have been occasions when a breakdown truck has been needed.
It's been in a garage a number of times with no verdict because it runs fine until hot. I thought it was getting sorted out after replacing the fuel lines and pump but it just went a bit further before the same story.
The fuel lines have all been replaced, also the fuel pump and it has a new glass filter, plugs, points, HT leads, coil and condenser. The carbs have been refurbished and its been tuned, all to no effect. I've tried lifting the petrol cap in case its a vapour lock but there's no rush of air and no effect. Winter or summer temperatures makes no difference.
It has had an electrical problem (an issue with the hazards switch), hopefully sorted today but, due to heavy showers I haven't ben able to try it out.
Does anyone have any suggestions as I'm at my wits end and will soon be losing another summer's fun?