Ford Repair: 99 Ranger rough starts, head gasket problem, upper intake manifold

Question
My '99 Ranger 4.0, 5 speed, 4x4 with 92K miles had the left head replaced a year ago to solve a rough starting issue. (It took my mechanic almost a year to settle on the head being the problem.) Now it's beginning to start rough again after sitting all day or all night. On starting, it idles like on 5 cylinders for 15-30 seconds. Revving the engine can shorten this time. Once it smoothes out, it runs fine until you let it sit awhile again. My mechanic replaced a fuel injector last week, but that didn't solve it. He says there's no coolant in the cylinders and no compression issues. But this is how we started before finally replacing the left head. Is this likely anything other than another head or head gasket problem? Thanks!

Answer
Hey Larry,
    That engine has that plastic upper intake manifold, and the seals are notorious for sucking air cold. They are rubber type seals that appear reusable, so make sure they have been replaced recently when this other work was done.
    Intake manifold leaks, low fuel pressure, or bad check valve in the fuel pump are all of the first things I check on those when cold startup problems are the complaint. Also check ignition system, and NO Bosch platinum plugs. They can cause a hard start on their own. I'm sorry it took so long, I had to wait for my lunchbreak at work. I hope you can use this information. Good luck!
     Shaun.