4G93 RPM too low, how to solve. . .HELP!!

[kl55]

guys.. i having some problem on my putra auto

i jz bought it back from used car dealer

year 2000 MMC thorttle body APM ECU

i having this Low RPM problem

ok i describe the problem

my rpm on Gear P or N is fine, if on air con, rpm drop to 600 RPM (i think it's consider low too. .right) but will come up abit, jz abit
and when steering turn left or right, rpm should be increase but mine is just like 50~100 rpm up only

now the problem
When i push to D, rpm drop till 100~200 RPM(on or off air con also the same), and my steering n dashboard start to vibrate

but engine still manage to run la. .
i clean up TB and adjust IDLE rpm but problem still exist

my friend just now test the ECU but no error code,
replace a thing call themorstart? in TB but still the same

so we suspect it's wiring problem

one thing is when we check the air con system
the wiring not going in to ECU but direct to compressor

my friend said this might be the problem coz he said air con wiring must go to ECU in out only go to compressor
but not confirm yet, he will check the wiring for me later, so the problem is still unknow

so ZTH sifu anyone experienced b4? pls assist me on this, TQ

 

[speed2horizon]

I suspect the ISC. Mitsu common with ISC problem.

 

[kl55]

ISC is what n how to solve
thx bro

 

[speed2horizon]

ISC = Iddling Stepper Controller

Replace it FICD

 

[frossbytes]

Bro r u planning to DIY or your current mechanic cannot solve it for you?