[fengmit]

My Camry 98 (86k) stalls intermittently at stop sign right off highway. Dealer replaced EGR modulator and vacuum switch valve and didn't fix the problem. Disconnected EGR system to test if EGR valve is the one having problem. Test drived 3 days w/o EGR and had no stalling. My friend helped me cleaned the EGR valve (was clogged with carbon) and run for 2 weeks (70miles/day) w/o problem. However, it happened again yesterday. I took off the valve and checked today. The valve moveed up and down ok when I pushed it by hand and also by mouth (simulates vacuum suck). Found only a bit cotton debris around the shaft, probably from previous cleaning. I did another round of cleaning anyway (use brake fluid). After I finished cleaning and put it back, I did a EGR valve test following instruction from Haynes manual: I started engine and let it idle, detached vacuum hose from the EGR vavle, then put the hose in my mouth and gave it a suck (manual says to use a hand vacuum pump - I checked Carquest cost $50). The engine stopped right away after the suck (opened the EGR valve to let exhaust gas back into engine). According to the manual, when apply vacuum to the EGR vavle, vacuum should remain steady (no leak) and the engine should run poorly (EGR valve should be closed at idle speed or will run poorly - my guess).
My concern is my case is not just running poorly, but stopped completely. Does this indicate anything else may be wrong? I tested again when engine was warmed up to normal, it took slightly longer to die. Does anyone know when exactly the EGR vavle should open and close? I'm still try to figure out whether the vavle is the problem or something else. I think the best thing for me to narrow this down is to disconnect the EGR again right after it stalls again (hope not happen anymore, though)! Any other suggestions / thoughts would be appreciated.