OK, Big Help Required Please

[t5fau]

Afternoon everyone,

I have a wierd intermitant problem on my 1990 8v 1.6 driver. 90% of the time its runs sweet as a nut, perfect idle etc, but when under heavy load (5th gear low revs for example) i experience the revs drop instantly (sometimes the engine drops revs to but not all the time). The violent rev drops make the car jaunt forward, and ive had a backfire as well.

Im aware of some general issues to help in my fix like ignition timing, worn distributor cap or rotor arm, and the low tension side of the coil.

I have already checked all the low tension cables from coil, any sensors off carb i can see and plugs, leads etc. compression is fine too.

Can anyone give me any more assistance in this matter, any weak components that would likely cause this problem, i once heard a "Hall" sender or something along those lines. Im 100% sure its an electrical fault, i just have £0 to spend and need to sort this asap.

Thanks in advance

[DarnPB]

Have you changed the cam belt recently? Was it fitted correctly?
Just a thought.

[t5fau]

no hasnt had a cam belt change recently at all. im 100% sure its electrical, just having problems finding where 

[herbster]

Check all the vacuum pipes, carbs don't normally play up like that unless the choke sticks on or the vacuum isn't working properly, theres a diagram in the haynes book to what should be where!