Average fuel increasing rapidly whilst at idle

ill firstly apologise for such a long post but I’ve had a lot going on and it may be beneficial or provide some insight.
Ok I’ll start a while back... I’d had all belts done in Oct 2016 and get average fuel economy of 8.9litres per 100klm.
Always had a idle which was consistent but with puffs and slight coughs. I tried a few things like I tightening seals on the map sensors which helped the most. But was still starting rough, idle dropping like it wasn’t gonna fire up, and once or twice conking out when trying to start up; once started she was always fine. Cleaning injectors didn’t work... helped idle a little though ie pufs etc.

About month or so ago I replaced fuel pump assembly with a item off eBay...
Then three days later the harmonic balancer crapped itself... so new balancer and aux belt. And new timing belt and bits there as it appeared the molten rubber had got inside the timingbelt “enclosure” covering it all in molten rubber.

So when I pick it up they tell me that Renault had setthe time giff one tooth. Ok that’s weird... so I go get my car and it’s running on idle rough... I say to myself “well last it ran the blancer was shitting itself and the ecu was probably freaked out. Plus the battery had been out for about ten days before the work was done, so maybe it was reset”.
Now since when pressing ignition it sounds like a belt is tight, like a tight squeak. And since that work it wont start first go but it always will on the second try.

Also since this work the A/C compressor won’t switch on at all (fans all blow etc) I can see the belt moving the pulley on the Ac compressor but when turning on the AC the compressor is not engaging...I thought maybe there’s an ecu code that needs clearing for Ac pump to be happy... but car provides no error messages and using a free version of Torque it shows no error codes.

So idle hasn’t improved over the few weeks since either.


OK now today... I’ve put in a new temp sensor which goes before the first map sensor... popped it in and ran car for ten minutes at idle (same low and rhythmic vibration occurring with more puffs etc then before the belts were all changed)...

...hour later I go to service station and notice the Avg Fuel rate was at 17.0!!! (That’s from an avg of 8.9 which I’ve had for about 18 months) Then every ten seconds went up .1.

so whilst I’m watching it’s gone up to 19.5 and increasing....so I take it out on the road and driving at 2000rpm and over it quickly (well every3-7 seconds) is working its way back down again. I don’t specifically recall checking the avg fuel since the belts were replaced but it’s always been something I usually check every time I drive... each other time I’ve ever had the battery off before it’s only taken a few days at most to level avg fuel to 8.9 at most.

Thoughts?!

i might clean back up the old temp sensor and switch it back in and see what happens?!‽
Could the timing be out and if yes cause this?!
Could the replacement fuel pump be giving too much pressure‽. ...or is it now it providing right pressure but the old injectors are squeezing out too much fuel‽

 

2006 RS Megane 225 Cup.
First timing belt change I had done (after buying from first owner) was with Renault. New water pump, tensioners etc. that’s was Oct 2016.
This work (for harmonic balancer) was an independent workshop. Here in Qld Australia we have no Renault specialists per se.
The workshop is known/popular amongst VW/Audi group owners for their work and tuning. The owner/head mechanic being a British bloke I trust him more than some mechanic around the corner. In Australia most mechanic shops work on what the market provides; so as you’d expect it’s a majority of Fords, Holden’s, Japanese,and korean cars. Whilst not exclusive, Renault’s are probably quirky and an easy way to get parts needlessly replaced chasing issues rather than diagnosing them.

 

SO I thought best to switch the old temp sensor back in... I gave it a good clean first as it was quite greasy and grubby...
Wife had to borrow the car for a trip ... 45mins each way...

And this morning I get back in the car and the Avg Fuel is now at 8.3 Litres per 100klm... WTF.... that's quite a bit lower than my year average and consistent figure of 8.9 ?!

Could I assume this eBay sourced temp sensor isn't compatible as the seller suggested. And some error in its feedback to the ecu is reading the car as hot inlet temps so its over fueling in an attempt to cool the inlet temps down?

I'll have to monitor it over next few days still.

*
no change to the idle or the A/C functioning still