Stop in for a cup of coffee

What’s wrong with your furnace?
Well I thought it would be the filter so I replaced that and new nozzle and even replaced the electrodes. Still no go. SO I noticed the nozzle is wet and there is fuel going in so replaced the (crap I can't remember what it's called) the black box with the contacts. Still no go. My buddy says it is the thing that determines when to turn the fan on. Oh and I replaced the eye