Car looses revs going uphill or faster then 90kmh

[TazzKatt]

Hi all..... my first post here, hopefully I've left enough info on the issue...
Its a '93/'94 Liberty GX, non turbo. I've been having this problem where if i'm going uphill or over 90kmh the engine looses power (put your foot down and it wont even revv up), starts getting really chuggy and stalls as the car comes to a stop. It's worse in the morning (i have to stop the car, turn if off and back on again after the bridge near my house) but will happen during the day too, depending on how steep the hill is. I have a couple ideas of things to try but would be handy to know if anyone else has come across this...

[Robbks]

It's called Lifter pump-up
after a sustained load, the hydraulic lifters that assist the intake valves have oil pumped into them and it doesn't drain away fast enough
the valves get held open, it loses compression and won't run

you need to do a good oil drain, flush and run some lifter-free through them,
frequent oil changes (5000km) using Castrol magnatec to keep them clean

[TazzKatt]

Thank you!! not sure why I didn't think of that... it did get better for a short while after it's oil change

[Robbks]

if they're bad enough you may have to pull them out and clean them out

I have seen them flushed by running the engine on a mix of oil and diesel
engine needs to be hot, oil drained, refill with diesel+fresh oil, start car and don't touch the throttle, let it run for 10 minutes
let it cool and dump it
refill with fresh oil

[TazzKatt]

where exactly are the lifters located? ( i'm reading the pdf of a workshop manual for the car and not sure which section they would be in)

[Robbks]

top of the heads between cams and the valves mate.

RSLibertyClub has the early service manuals stickied there for easy download

[TazzKatt]

That's where i got the manual i'm reading now. I'll be trying this out tomorrow morning so we'll see how we go, Thanks heaps