95 Corolla, 200k miles, 1.6L engine with auto transmission. Last smog check a couple months ago I almost fail with high Nox, normal HC and CO, and have to pass with retest. So a couple days ago I did an EGR clean up (taken out EGR valve and EGR hose and spray with parts cleaner) and engine bay degreasing with Simple green and buckets of water. Afterward I noticed the car would start in cooler weather then quickly die down. It happens consistently for 4-8 times, the starter sounds normal as well as the first ignition, and the way it stopped sounds like I turn the engine off after a normal drive. If I hold the acceleration partly it would not stall until I let my foot off it. However if the weather hot it would start on the first try and the drives afterward is normal. I've done the commute 4 miles each way for at least 2 times already and it never stalled while driving. I'm planning on changing the fuel filter before this so I already have the part, but I am postponing it until I I figure out why it would stall. What would it possibly be?