Misfire on acceleration

[DanTheDoc]

Apologies for jumping in with a technical question, I think I’ve exhausted the help on another forum.

I’ve got a problem that is driving me crazy. I’ve got a 1991 Mk2 Golf 1.8 Driver Automatic with Weber Carb. I’m getting a bad misfire when accelerating/driving in the lower rev range. It idles absolutely fine but wants to stall from standstill when I put my foot on the accelerator. The revs kind of blip up then drop off dramatically. The only way to overcome this is by ‘breaking through’ the misfire section and basically flooring it. It drives fine when you’re driving like a maniac but this obviously isn’t feasible.

The other very weird thing is that when I picked it up from the garage, it drove amazingly, probably the best it’s driven since I’ve owned it. But the next day, the misfiring was back. I have absolutely no idea what the connection is, weather maybe?

Here is what I’ve done so far:

Found a vacuum leak, replaced the hose.
Air inlet flap to the air filter seized sucking in hot air, freed up the flap.
Serviced the carb. Twice, once with new needle valve, once with old needle valve. I didn’t touch the jets, just sprayed them with carb cleaner and blew through them with air.
Changed the HT Leads for a new set.
Spark plugs are only 5000ish miles old, as is the fuel filter, air filter etc.
Checked for more vacuum leaks, none.
Had the timing checked, fine.
Had the mixture adjusted by a garage, they said the mixture is now fine, was only a bit out. They also said that the hydrocarbons go up through the roof when you accelerate as if it’s either getting flooded or not igniting.
And lastly – topped up from an empty tank with petrol from Tesco(?) (First time I’ve used Tesco petrol in this car)

Here is what I am going to do:

New distributor cap
New rotor arm

Does anybody have any idea as to what the problem could be? Your help would be much appreciated.

I’m running out of money, time and wife patience.

Thanks

Dan

[JamesSvr6]

I used to have this engine in my mk2 driver with a 32/34 DMTL Weber. I got throught 2 of the rubber flanges in 18 months that the carb sits on. When they split air is let into the manifold and the car would missfire, splutter or even cut out when pulling away unless you floored it. In order to pass emissions the carb had to be leaned right off to pass MOT, which also made it almost undrivable. Try making the mixture richer and see if the misfire goes, if not take the carb off and check/replace the rubber flange (not much from GSF). Check earths also, poor earths can produce weak sparks.