380 SEL cranks, has spark will not start

[73cudaproject]

Hello, I have a '82 380 SEL which just up and quit running at a stop light. The motor cranks just fine, has a fairly strong spark, timing chain seems OK, fuel pump is working. Last night I removed one injector (left it on the fuel line) and cranked the engine. Injector puffed one nice cloud of gas then nothing but maybe a dribble. I would quite cranking, wait just a moment to crank again and again the injector would puff one time and then no more nice puffs. Any ideas? The plug (only checked one but it was a different one than the tested injector) seemed very dry. I appreciate any advice.