Jtrnz03

Recently changed sparks, coil packs and in tank fuel filter. Also cleaned TB and maf sensor. The rpm still jerks on idle ( on D or R).

BUT WHEN I TURN MY HEADLIGHTS ON THE ROUGH IDLE STOPS. pls help ..

xGS350x

Use an OBD scanner to pinpoint the issue.

Check hoses for any cracks.

Jtrnz03

Nope nothing could it be when i replaced my new battery?

xGS350x

It might depending on what battery you got.

If it were me, I would get a better OBD scanner to pinpoint it. Don't replace parts after parts to fix the issue.

richieca

When did you do all this sometimes the throttle body has to adjust after the cleaning and it goes away.

2ndgenftw

I had this same issue with my 1997 LS400 i replaced all the motor mounts transmission mounts and differential mounts, cleaned the idle air control valve and the idle up air control valve located on the power steering pump and it resolved my issue

Marc780

I happened to read this older post and got curious - did you ever track down the problem? You've got me curious alright!

...on first reading your symptoms I was thinking something like there's a cold start injector, stuck EGR, maybe just a dirty throttle body. Then at the part where "I turn my headlights on the rough idle stops!" My first thought is of course A) electrical issue where something is getting the right voltage some time and not enough voltage the rest of the time. And as it happens, sounds a little bit like a problem my dad and I had with his old 1977 Dodge Ram pickup, long ago. Long story short, rough idle sometimes, smooth idle sometimes, we couldn't diagnose it so I took it to a shop. Their mechanic tracked the problem to: the ignition switch!

And of course that was literally the very last part I'd have checked, because I'd never have suspected the ignition switch could even effect engine idle, but it did. It was only after the fact that I realized, of course, all the electric power for everything goes to or from the ignition switch, and the long-term wear on the switch was somehow effecting the voltage to everything else including the ignition system.

Point being, in troubleshooting it helps to look at every part involved as a system, since if the problem isn't obvious, it could take some real detective work to ferret out the problem! I'd check the engine ground connections, the battery ground cable for rusty loose connections; plus check the EGR, clean the MAF plus the aforementioned throttle body - if nothing obvious is the problem, to me it is time to admit defeat and take it in to people that know these cars backwards and forwards, i.e. the dealership -