On a cold engine first start of the day the RPM's will dip down to 400-500 right as I stop at a light or stop sign and then jump back to 700 and idle fine. When it does this I can feel the engine sputter. Other times when I stop the engine will flat out stall - RPM's will just drop to 0 right after stopped and it always starts right back up and runs fine. After 10 minutes of driving this issue seems to rarely happen. It seems worse on cold days. Sometimes on cold days on cold starts when I back out of my driveway and stop, the RPM's will dip to 400 and the engine stumbles, and then idle jumps back to normal 700rpm. Also when the engine hasn't fully warmed up on cold days like a minute after starting and I go to drive, it lags a bit on acceleration but clears up after a few minutes. I can also feel vibration in my seat and the vibrations clear up somewhat but it's always there on a hot or cold engine. The vibrations were never there until this idle/rpm issue started happening.

I've cleaned the throttle body. I've cleaned the MAF sensor. I've cleaned the MAP sensor. I've replaced the crank sensor. I've replaced the intake manifold gaskets. I inspected the intake manifold for holes/cracks didnt find any. I've replaced the fuel injector o-rings. I've checked all over for broken wires and sprayed all over for vacuum leaks. I've cleaned the fuel injectors and checked spray patterns. The fuel injectors don't leak with the key turned on or off. I've ran techron through the gas tank a bunch of times. I've checked fuel pressure and it's 60 psi at idle, 50 psi with key off. Compression is around 180psi on all 4 cylinders. I've replaced the spark plugs and boots. I've replaced the ignition coil/cassette. I've blew through the EVAP purge solenoid and left it disconnected and car still didn't run any better. I've checked battery voltage and disconnected battery and let it sit overnight. I've pulled valve cover and the timing chain is tight and not loose. I don't have any timing chain rattle noise/rattle either. I was getting a startup rattle from exhaust manifold and found 2 studs loose and once I tightened them the noise went away and it's been 2 months now.

And the worst of it all is that there are NO CODES.

Is it possible maybe it could be the throttle body sensor or possibly sensor failing? Maybe maf or map sensor? Maybe unplugging the MAF or map and seeing if it runs any better? I've done everything I can think of. I do have an obd 2 that shows data.