Isuzu Mu Wizard 1997 3.1 auto slow gearbox change

[LiveEvil]

Hi all,
in a fantastic/cruel twist of fate I ended up purchasing an old wizard with 3.1 liter 4jg2 engine and automatic gearbox recently.
I don't have any experience with mechanics unfortunately
First i had the issue with throttle cable which i managed to fix.
But before it broke and after it fixed i am experiencing a weird automatic behaviour. At start it seems fine. But after certain amount of time or stress (say going uphill and then down the road) gearbox does not want to change gears.
It overrevs but i have to play with throttle before it starts changing.
Maybe there is something overheating or gearbox cable is not set correctly.
I would appreciate what would other ISUZU club members would suggest to do about it.
Image: https://i.imgur.com/3q9UYw0.jpg
Image was taken before a fix so dont be alarmed by tie-ups . They were awesome anyway.

[geeves]

2 Things that might cause this are the throtle position sensor and the kick down cable. The first post in the general isuzu discussion folder has a link to a Frontera and bighorn workshop manual. The Frontera is your car except it doesnt have your engine. You need the bighorn manual for the engine and gearbox and how to test these parts and fix

[LiveEvil]

geeves wrote:2 Things that might cause this are the throtle position sensor and the kick down cable. The first post in the general isuzu discussion folder has a link to a Frontera and bighorn workshop manual. The Frontera is your car except it doesnt have your engine. You need the bighorn manual for the engine and gearbox and how to test these parts and fix
Thanks, both of these suggestions make sense. Damn, i really need to start reading the service manuals. My only complaint is that they are so big.

[geeves]

The car or the manual?
The manual fits on a cd which is tiny

[LiveEvil]

geeves wrote:The car or the manual?
The manual fits on a cd which is tiny
Manuals . The ones i found are around 3000 and 10000 pages. The car itself is awesome. Another question. Is there a place i could source the fascia of the instrument cluster. You know the plastic around the gauges, ac and stereo?

[geeves]

Those manuals work best on a pc Just print the page you need
Facia best check wreckers but I know these are not common over there. Facias are not a part often changed