I have a 91 E-350 351w with a tfi distributor. I have been having intermitent ignition problems for a couple of years. Now the problem is constant (no spark). Has anyone had a tfi module crap out on them in this way. I am not convinced that of my diagnosis.

 

It sounds like your TFI module. I have had them go like you say.

 

Thanks, replaced today, runs great. Glad thats over.