03 hilux 2.7 hunting on petrol

[shitbox hilux]

Hi, i am trying to fix a friends 2003 3RZE Hilux
the car runs ok on LPG but on petrol very rich black smoke out of the exhaust
at idle it runs a bit rough
when you rev it to about 2500 it starts to hunt severely down to about 2000 and then quikly back up to 2500
its showing no codes
ECU is fine
Fuel pressure fine
Air mas sensor fine
TPS fine
Coolent sensor fine
new leeds plugs
a friend told me it could be the fuel pressure regulator but that seems ok
another friend said maybe throttle body could have warped after it backfired realy badly and burnt the old air mass sensor
maybe blocked injectors
Has anyone had this problem
its driving me mad
Many thanks
Bluey

[Clubber997]

I've never had this problem, but I'm just throwing a couple of ideas around. Has it had a LPG conversion? If so, it probably shouldn't be running on petrol at all... If you're sure its not a sensor, has the ECU been intercepted/reprogrammed for LPG? Is it running a different cam, or different injectors for LPG? Are all filters fine, and is the fuel pressure ok? (It might be too high because of a restriction on the return line, if it has one). Anyway, let me know how you go.