20v 4age Silver Top Idling Issue

[022]

Hi Guys, I hope someone can help me out with this weird situation.

Its a 20v silver top 4age in a 1992 Levin. Only done 90000kms.

From cold start the car idles perfectly fine and runs fine doesn't miss at all.
Car warms up after a few minutes and still runs fine as long as you dont use anymore than 50% throttle. Can run the car all day long and runs perfect. As soon as you put throttle over 50% the car start missing and idling really bad when your not moving. As long as the car is under load, (driving normal conditions) you cant notice anything wrong with it until back at idle it will start missing. Its not revs based, as you can use only up to 50% throttle and rev it to at least 6000rpm and this will still idle fine.

Another situation.. after the car warms up and running perfectly fine, can be sitting in neutral and use 100% throttle for the shortest time possible, (car only revs to 1500rpm) back at idle again it will start to miss and sometimes stall.

Car doesn't go back to normal idling conditions until the car has cooled right down again.

I've tried cleaning out the ISCV like other people have suggested on here and got a bit of black liquid out of it but this hasn't changed anything. clean out the distributor cap and measured all the high tension leads all of which is good. Have also just changed the capacitors in the ECU as i was told these can leak and cause issues with rough idling. This has also not solved the problem.

Hope this all makes sense and someone can help me out as i'm completed stumped now

Cheers Paul

[Dell'Orto]

Have you checked the diagnostic codes?