Just a thought: did you check your battery voltage? What about the OVP? If that is good, what I would do is go back to the beginning....What I mean by that is start from the throttle body and work your way up. You've already established fuel and good spark, so the problem will most likely be found between the throttle body and the injectors unless the O2 sensor causes a no start, which I doubt. So take everything off down to the manifold where the throttle body sits. This will give you a nice bird's eye view of things, it will also allow you to check the integrity of the integral parts of the air components. To get everything off including the throttle body is roughly a 15 min job so it isn't bad at all. But before you begin I would make sure you have a set of various size o- rings, some carb cleaner, gasket material (autozone sells the gasket material, the rubber/paper for the throttle body housing), a couple feet rubber hose for vacuum connectors, and also the IACV hoses. The IACV hose is the only specific thing that you need to order. These other parts are necessary so that you can replace the o-rings on the nylon injector guides, various vacuum tubing since everything is off, the throttle body gasket. Tools you need to complete this job is: 10mm socket for the nuts on air cleaner and nuts securing the wiring harness and fuel distributor; 17mm wrench for main fuel line and return hose; 14mm wrench + 5/8 inch wrench (14mm for the fuel injector lines, 5/8 to fit around the metal guide so the injector doesn't turn); 12mm wrench for the cold start valve; 5mm hex for the bolts holding in the injectors and for the bolts on the throttle body; Phillips screw driver to undo the clamp fastening the rubber boot on the fuel distributor and to undo the TPS attached to the manifold (not the throttle body). From here you can bench test injectors, and check the integrity of everything. Also you can now see into the manifold and see if there is oil pooling inside, which would mean worn valve stem seals. Note: you do not need to remove the IACV to get the fuel distributor off, you only need to disconnect the hose on the right from the IACV. If your hoses are good, then you don't need to replace them. I know it seems like a lot, but I can literally have my throttle body and all the above mentioned components off the car ( 2.6L) in 15 minutes. Good luck.

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1990 190E 3.0L