Sorry for the novel but I wanted to be as descriptive as possible.

I've had my SC for a little over a year now and she's sitting at a little over 230k miles. I've put about 20k on it, and in that time I always been prompt on my maintence, even spent a little more on royal purple fluids.

When I first bought it, when putting it into drive or reverse it wouldn't engage for about 2 seconds and then it'd jerk hard when it did. As it got more cold reverse got real funky. It'd take up to 7 seconds to engage, it'd work for about 2 seconds, then it'd disengage for 7 seconds again and just roll, then catch and work fine. Drive stayed the same, but once it got warmed up they'd both work normal. Still though, it'd jerk hard when engaged.

those problems, minus the hard engagments went away. Fast forward to this winter.
It started off with a loud, what I would assume belt whine that would change pitch when you turned the wheel. The old trans problems came back. Now about a week ago the big issue popped up.

The car is sputtering hard at low rpms. Off a winter cold start it drives fine up until you stop and have to climb the gears again. Once it hits about 2k rpm though it drives normal, and it goes down in gears normal. Once it gets back down into idle it starts acting up and so on through the gears. When I go up hills at low rpm and have to give it a little extra while it's bogging, you can hear a pop about every second you're doing it. It's not loud, but it's not quite and inside it sounds like it's coming from around the back seat driver side. Also in neutral it revs without sputtering, but once you let off the throttle it makes this subtle, kind of like, metal rubbing metal.

The problem started randomly as I took off normally from a right turn at a stop.

I did some searching and ended up replacing the fuel pump with a OEM replacement from High Flow Fuel Performance. The problem remained.

No CEL either.

Any ideas?

 

Ignition coils could explain the sub-2k sputtering (~1400 RPM, in my experience), but the noises are unfamiliar to me.

Transmission issues could be a sign that the ECU needs servicing. The cold/warm behavior is tough to explain in that respect, but I had a knock sensor issue where the ECU pins and traces were corroded badly enough to barely make a connection, tripping the CEL and limp mode usually when it warmed up.

 

Your post prompted me to do some reading on the coil failing. Looks to be about spot on with my issues. Will give that a try. Thank you for the response!

 

So I tested both ignition coils. Neither ran by themselves. I pulled off the intake/maf because I wanted to look at my spark plugs. 6 weren't seated right so I fixed that. Without thinking I started it without intake/maf and it fired up and ran normal so I'm like kden. Get everything back on it goes back to running poorly. Unplug the maf, it idles fine. I plug it back in, drive a half mile poorly. Unplug maf again (did it while car was on) drives fine until I stop. Now instead of just bogging and dipping its a constant drag. Did I just mess up my maf?

Also I'm not sure how the throttle body is supposed to look on the inside but the first "flap" stays open. I can move it freely with ease, but when its running its stays wide open.

I'm getting very frustrated

 

When I said 6 weren't seated ride I meant the plug wires

 

The TB plate should be closed at idle and fully open at WOT. I don't have any experience with how much it opens at different amounts of throttle.

These early MAFs are very sensitive buggers. It could be that you got some gunk on it, or it could be dead and the cause of your problems. You can get a used one for ~$25 to try out.

 

Since the ls400 has the same engine will the maf and tb work with it? There is only one 1uz at local salvage yards and its in the ls

 

Check the part # on the MAF. I believe the TB is different, based on the recent dashpot thread.