[4AGE] ignition timing problem -> SOLVED !!

[eg6maxx]

I've got a big problem on my 86.

I used the search engine, I found some threads about the ignition timing issues, but they didn't help me.

About 2 months ago I decided to check the ignition timing on my 86 with a stroblight.
At this time the engine made some backfire but run fine, I though there was too much advance. I was right.
The ignition timing was a pain in the *** to set at 10°, and yes I jumped the diag connector :wink: .
Since that day I can't make my 86 run normaly:

Ignition set @ 10° -> iddle is fine but engine can't rev up, the car can't run without stall.

Ignition set @ ALOT -> iddle very high (1200-1500rpm), engine can rev but a lot off back fire/ missfire, the car can run but it's a mess.

I worked on that sh** about 2 months...
What I've done so far:
- I set the dizzy to all the positions you can imagine, when I bolt it in place I tried with 1 or 2 teeth in advance or retard. I bolt it in place with or without the rotor cap and the cam cover to watch the teeth.
-I changed for OEM BRAND NEW: Coil, Rotor cap & rotor, spark plug Denso Q20R-U11 (My IQ20 weren't very old) spaced to 1.1mm.
-I tried with a brand new distributor.
-The cords are TRD ones about 1 years old (1000 km maybe)
-O ring is new.
-I tested the igniter and the distributor : no problem.
-I checked all the vaccum (map...etc...) for leak : nothing found.
...

The ECU doesn't have any error code.
When I jump the diag connector to set the ignition timing @ 10°, it's very difficult to set, (engine at working temp and iddle set @ 800-850 rpm) the "TDC" mark "jumped" some times. I guess it doesn't have to do that because I jumped the diag connector.



Engine is 4AGE Bluetop, about 150k, it's the original one (1984 Zenki Corolla GT MAP sensored).
Only mods are Apexi Air Intake, Techno pro Spirit header and HKS (Silent Hi-power) Catback.

Maybe the problem is not the ignition timing, I'm kinda lost...Please HELP ! Thank you very much.