Motor revs up and down on steady throttle

First of all I hold my head in shame as I have not been around in a ****'s age.
After the big crash of the tuonozone website way back when it was almost the same time I bought a Gsxr 600 to put on the track and since then it's shifted my road riding to mostly setting up the bike and track days. I must say I'm having the most fun I've had on two wheels since my days of racing motocross back in the 80's.

Long story short is a little problem that was creeping is now reared it's head.

Throttle response has been lumpy the past few months between 3000 and 4500 rpm. Not too bad mind as it's never been perfect but being I know this bike better than any I've owned before I could tell it was running off and tried balancing the throttle bodies a couple of times but still really lumpy.

A few days ago the injectors just jumped up and down at a steady throttle. Keep er anywhere between 3500 and 6000 now and she wont hold a steady rev just up and down and not fast pulsing but like the fuel injection cant tell what the throttle is doing.

First I checked all vacuum lines as this is my first thought, all clear, lines are new and connections are good. The bike isn't throwing a service or code so I'm not confident it's an electrical gremlin. Neighbour reckons bad plug but I'm not seeing and backfiring or dirty end pipe to suggest one cyclinder is packing up.

Aprilia shops here are fugging useless as i'm willing for them to just hook it up to a diagnostic but they're all talking weeks of waiting and big $$$$$.

What thinks yous?

you, know, I did a frame swap back in november and I coulda sworn I dropped new plugs in but I'm just not sure. Guess tomorrow I've got to pull her apart and check the plug leads and plugs but man, what a bitch getting to the front cyclinder plug. Royal fuggin pain that.
I'm tempted to bring er in to the shop but I bet it's something small and the shop will charge out the *** for something small or obvious that I'm not looking at yet.

So was going to bring in to local aprilia shop and describing the symptoms he said 90% sure it's the fuel pump and there's probably a leek inside. Pulled the fuel pump and all looks ok but need to do a fuel pump test but not sure how to check 48psi without gauge. looking more for any leeks from connecting hoses but with flammable liquids and need to use outside battery it's a bit dodgy trying to find a safe way to check fuel pump when out of tank.

Well, 4 hour later and it's not any fuel pump problem. Pulled the pump, checked the filter but did'nt change the canister filter and ran tests. Submerged the filter in white spirits as I did'nt want to blow myself up. Hocked up an external battery and ran the pump. granted I don't have a gauge to check for 3.3 bar or 48 psi but I blocked of the fuel line and the pump pressure valve kicked out fluid so the pump was at full pressure and didn't show any leaks or loss of pressure as it was chugging fuel out no problem and purring like a kitten. Looked all over for any leaks but all was well and the pump itself had the recall 4 cm line in it so that had been done beforehand.

pulled plugs and they're white, too white, very lean and that's got me suspicious but other than the idle screw/mixture on the throttle bodies there's not much one can do to run it richer or if anyone knows how...?

starting to suspect plugs, electronic, coils, something along those lines as my Triumph trophy been having similiar problems but cutting out on the highway and I suspected vapor lock or some type of fuel starvation but in the end it's the coils so ordered a new set of those for it.

Bike at steady throttle seems to skip, hesitate, like plugs are cutting out .Can't really be fueling now cus it's too abrupt.You'd have to chop the throttle off to get a hesitation like that. Throttle position sensor? Mystery goes on.