2000 Suzuki Vitara 2 liter stalls when engine warm

It's on the left front when sitting in the car.
firing order:
1-6-5-4-3-2
See the bottom diagram at this site:
http://www.autozone.com/repairguides/Suzuki-Vitara-Grand-Vitara-XL7-2000-06/Firing-Orders/Firing-Orders/_/P-0996b43f8037c759
GET 25 GIFT CARD FOR EVERY 100 SPENT ON ONLINE SHIP TO HOME ORDERS

lost engine power, or transmission slips????
which is it?
the engine rpm tells you if the engine is weak or transmission slips.
2.0 liter , DOHC I4, J20 engine.
which transmission, my guess A/T box. (sounds like?) sure..
test one
1: in drive. pointed in safe direction, say a field or ?
2: parked, hand brake and foot brake held hard and fast.
3: race engine to wide open throttle for 1 to 3 seconds.
and lift right foot. after noting RPM. quckly.
4: rpm below 2200 rpm is a weak engine , if the engine spools
wildly up to 3500 rpm or more, the transmission is bad. (slips)
this is called the stall test. (in the FSM)
2,300 - 2,600 r/min. for H25/J20 engine
stall test passes. so does the transmission reach 4th gear.
1,2,3,4? yes/ .no.
yes, the its not the transmission.
if engine power lacks in any gear, that is the engine. weak.

this post is about the engine power, (my answer)
will you change 100 more parts guessing?
why do that?, any shop can diagnose it for a fraction of your guessing.

if the trans dont slip

1. over heating? the engine?
2. never done a tuneup this decade?> really?
3. low fuel pressure?
4. low engine compression.?
5. Bad MAF sensors or just dirty?
6. check engine light on running?, why ignore that, scan it.
7. weak spark , see #2 and 6
8. leaking or clogged injectors. or stuck on, for 2 reasons.
9. Intake vacuum air leaks>?

both the engine and transmissions are complex
as is the vast number of tests to do. based on previous tests and logic.
do you want to test or gue$$?

doing engine work, FSM free?
alldata.com

has this.
or
https://suzukipitstopplus.com/Products/10218-2000-vitara-grand-vitara-service-manual.aspx

just 4 bucks.
and see all the other mistakes you did,

you mean the firing order ...... for the drivers side its 135
the passengers side 246

https://suzukipitstopplus.com/Category/3-suzuki-service-manuals.aspx

Did they figure out if you are loosing fuel or spark when it fails to start up ? You would need to know which to proceed.

old post.
http://www.scantool.net/software/alldata-diy-1-month-subscription.html

the answer is this in USA, are you>?
open hood, look up ,behold the white sticker, and is there.
all suz. have a timing freeze jumper, starting in newer years its a factory only scan tool setting.
on yours, must 1.6L , the liters tell me what engine not valve count.
to set timing, you need a strobe light , got one?
1: hot motor.
2; idle rpm perfect. not too low, or high.
4: timing freeze, enabled.
5: set timing with strobe , using under hood sticker data.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve but always run a OBD2 fault code as well as the cleaning procedure. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

Air control valve maybe or it could be an intake or vacume leak