Mk1 golf fuel starvation ???

This is a long winded story so bear with me and apologies in advance……..lol

I have a 82 mk1 golf gti with a 200hp 20vt. 

I removed my accumilator so my car is basically now tank-pump-filter-motor. Reason being is simplification and the accumilator and hoses were rotten.

Since I I did the job my fuel pump sounded bad after about 5 mins and performance was totally killed and barely ran with the slightest load on the engine. I replaced the fuel pump with an aftermarket version. But in the process of replacing it I found that the original pump had collected aload of debris in the pre filter which caused fuel starvation. So I replaced the fuel
Pump any way and ran sweet plenty of performance. After a day the car ran bad  again but only under boost conditions. I found out that new pump had a one way valve in it which had jammed causing poor flow. So i drilled the valve out but the pump was kerputt, So I put the old pump back on again and drives really well apart from when you drive it hard you can feel the power fluctuating slightly which is annoying .

Have I damaged my old pump which is causing fuel pressure issues ? Or is it to do with the fact that I need some kind of reservoir to store fuel due to starvation. Funny thing is I put all my accumilator back on again but it's exactly the same so somewhere along the line Ive caused a problem . Would there be a problem in plumbing the accumilator in wrong ? I can't see how as it only goes in between the pump and main filter. 

I'm running a cavalier fuel filter but
Has been fine the last few years and the fuel pressure is the same with it disconnected before or after. I recently changed all the fuel pipes too. The old pump sounds happy too though I have to admit its not as loud as before.

HELP !! Confused.com all I wanted was it to be simple and reliable !!

Also the car ran better when I had more fuel in it so I'm guessing its fuel
Pressure issues 

Check your tank for contamination ie rust in the inside, access this from the hatch below the rear seat and try fishing a magnet around in the tank. I would say either your main fuel pump is not keeping up with demand or the pump filling it. Perhaps make some form of swirl pot up after your lift pump but before your main and feed your return line back into it to see if that helps.

Yeah sounds like you've damaged both pumps there.

switch the non-return valve for an m12x1.5 barbed adaptor off ebay, and you may want to redo the lines if they look ropey. might have debris in them too from the tank? take the pump off again and see if there is any more grot in it, and clean the tank out:
http://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=how-to_2%2Ffuel-tank-cleaning_3

no need for the accumulator on EFI so thats definitely not the issue