Random Slow Starting

I used to prime my fuel pump for 3 seconds, or 3 "beeps" before I would attempt to crank over the 4.0L. It would start within 1/2 second.

One day I was in a rush to do somethings and forgot to prime the pump. It took about 5 seconds of cranking to finally turn over the engine.

Ever since then even while priming the fuel pump the engine will randomly start quick or slow. I have noticed that sometimes the longer the engine sits cold, the longer it takes to start. But other times it can sit until it's completey cold and start right up.

Any suggestions as to what the problem might be?

Get a fuel pressure guage on the rail and watch the pressure.

If the pressure is low? I'll do this when I get some time. Gonna be pretty busy before the weekend.

So if the pressure is low then what? What if the pressure is fine?

Just trying to find out some other steps to pursue before I figure out that the pressure is fine and then I'm stuck waiting again. Thank you for the help though!