Revs going up and down...

[Okami]

Hi guys,

Problem started a while back when we needed to fix the better exhaust etc.
So some time ago the Timing came of for the sparkplugs on my 1st gen 4agZe...

After that the car needed to start and ran a little bit low.
I have tried lots of stuff to get the (timing) to work but never came any further than how the car was doing.
It was fine I guess...

Now (yesterday) I installed a 160LPH fuel pump and its really really weird.
When the engine is cold it goes up and down the REVS - then when the engine is warmer it's fine most of the time after driving a couple of miles.
In reverse its sometimes more noticeable.

MOST of the time when at idle it goes up a little bit and then down and then it just stalls. It just dies... (need to restart)
When driving or flooring the pedal there are NO hiccups or problems.
So its really weird!

What do I need to do? Either place the throttle response or go to a dyno and let the mechanic TUNE my car OR WHAT?

What can I do?
Anybody in the Netherlands that can help me for some money?
Thanks!

EDIT : Friend of mine said maybe your drowning the engine... So that means I really need a tune-up or maybe something else...
Because of the Janspeed exhaust I also do not have a LAMBDAsensor anymore but before it was fine without it.
I still THINK the car should be timed properly.
But it can also be the Throttle Position Sensor