Determining if Starter is slowly failing?

[biscayne]

2000 F350 4x4 120,000 miles.

Here is the list of repairs and my hard start problem still exists.
1. Stancor relay mod
2. Probed all Glow plugs good
3. replaced mismatched batteries with Motorcraft 1050 CA/ 850 CCA batteries
4. replaced failed ICP sensor (oil inside plug only)
5. New HPOP right before I bought the truck
6. Took fuel bowl off and resealed it and replaced filter

Truck will turn over and never sound like it is going to catch, next try it will start to catch but if you let off key, it stops dead. Third time it turns over and at about 5-7 seconds you can hear the motor start to turn and the charging system light start to blink out then if you hold it 3-4 seconds longer it will run just fine. No other starting issues the rest of the day. This is in 40°F temps and it had been off for 12-15 hours. I almost killed both batteries the other night when I drove to work in 34°F weather and the truck sat for my 12 hour shift then I tried to start it in 24°F weather. 15 minutes of alternating and letting the batteries restore to equilibrium but it finally caught.

Is it Possible for me to determine the starter's health? I can go buy a $170 new starter from Advance Auto but don't want to keep throwing parts at it.

I think I have a sticking IPR due to the overpressure code I get when full throttle for an extended period of time then suddenly let off, could that be affecting the hard start? Any ideas are welcomed.

[jesilvas]

We can keep guessing like you, but you're not gonna know for sure on the IPR unless you monitor it's duty cycle.
Is your UVCH to the GPs good?
Maybe you have having an issue building LPO or HPO.

[biscayne]

I just didn't know if there was a way to verify a starter's torque built on the truck. I think I am definitely going to try KMA Towing's suggestion and SeaFoam the HPOP reservoir. My truck was admittedly neglected for a long period of time by the previous owner (due to not driving it) and I feel that all the sitting it did prior to me owning it did it no good.

[jesilvas]

I'd RevX it.

I made my Samsung SGH-I997 send this.

[kaya@bernhausen]

are you getting smoke out the tailpipe when cranking?
have you tested to see that the GP relay is even coming on?

[biscayne]

smoke and fuel smell was very strong the other morning when it was 24°F outside and the truck almost killed the batteries trying to start for 15 minutes. Any other time there is no real smoke. I replaced the starter today and I have to admit it spins noticably faster than the old one did. I just never had a starter fail like this...losing torque but still starting. All of my starter failures were catastrophic. I am keeping my fingers crossed, we will see.

Oh yeah, I put the seafoam in the HPOP reservoir....figured it couldn't hurt.