Very confused owner !!!!

[LeicJim3a]

A bit of a story here so I will give as much info as possible in the hope of finding answers. Car is a Robin Hood 3a 1983 2.0 pinto pretty standard. I have done much work 2 weeks ago went out in the sun it drove perfect and was stunning fun. Went into the garage last week for MOT and couple of minor repairs steering and suspension only. It cut out on the MOT ramp. Struggled to start the following day they got it running but was lumpy on tick over. I went in to them yesterday with a timing light and we set timing to 10BTDC I was very confident in the timing and it ran and ticked over smooth as anything. Let it go cold fired her up first turn of the key no throttle or choke or cranking over required this was a first ! We was 100% confident. A job well done. Left it ticking over revved her up absolutely spot on. Pulled out on to the road and a massive flat spot a chug a bang and limped straight back onto the forecourt it cut out. I fired her back up it chugged into the garage I turned ignition off massive bang and smoke out the top of the carb. Left it a minute fired her up ticking over and reviving beautiful at stand still went to pull off again same scenario !!!! Massive flat spots popping and banging out of both ends. The car has new dizzy and carbs fitted. My question is …. Does this sound timing related ? I was very confident with timing but now massively doubting myself ! Or should we be looking elsewhere to solve. 
 

any ideas and feedback from experienced pinto nuts appreciated 

thanks in advance 

[LeicJim3a]

Video of timing we did get it closer to the thinner line slightly 

[dandan62]

Out of interest, what make of dizzy is it? If its Accuspark I recommend you look up all the issues the new ones have and don't start the engine if it is. The new ones have a reputation of chewing up the Jack shaft sending metal around the engine. Just a thought. 

My 7 year old one has never had any issues.

[LeicJim3a]

I fitted a bestek dizzy following accusations horror stories 

[tractor]

that sounds like a fueling issue 

[LeicJim3a]

I’m starting to think it is fuel as well  I have 2 x inline filters one in the boot straight after tank and one just before carb. They both look clear but neither seem to fill up completely. I’m going to try and blow back into the tank tomorrow guessing there is some debris on pick up. I also have a new fuel pump so will stick that on as well. It is strange how it will rev through sweet standing still though only plays up when you pull off

[Derek]

I had a similar problem with my pinto engine, OK it was an EFI system though.

After many days of pulling out hair, it turned out to be an earth on one of the EFI modules.

The wire core had rotted away but the insulator had remained attached to the connector so the break was not apparent and it was making an intermittent connection.