1992 Ford Aerostar Car idles down and dies whenever it come

1992 Ford Aerostar XLT 3.0 minivan, 185,000 mi, when at a stop light, it idles-down and then stops running like it's not getting gas. It starts right up again, but does the same thing at the next light or stop. It drives fine otherwise. Before this started happening, the engine had a bad shake when stopped at a light, but no "check engine" light. I had a neighborhood mechanic change the plugs, check the coil, do a tune-up, adjust the timing, change the water pump and fuel filter, change oil and oil filter and top-off the coolant. It ran a lot better after that, but it still had a shake when stopped at a light, although not as bad now (still no "check engine" light though). I took it to another mechanic, regarding the idle problem. They put it on a scanner, but said the scanner says there is no problem. They also checked the fuel pump and fuel pressure; both OK. After I got it back, the "check engine" light is on all the time now, and it completely stalls-out when idling at a stop. Shifting to neutral helps it stay alive for a few seconds longer, but it still eventually dies.