Jeep struggles to stay cranked

My Jeep has started struggling to stay cranked unless I have my foot on the gas when I turn the key. It started "surging" while I had a steady pressure on the pedal. To "fix" it, I would let off the pedal and it would clear up for a while. I changed out plugs, wires, cap, and rotor and tps. Helped for a while. That was about a year ago. Now the "surge" is back, but not as often, but this hesitation is crazy. I don't know if it makes a difference, but it did not want to turn over the other day. Could have been a one time thing, but who knows. It now has a brand new tps, new iac sensor, and a squeeky clean throttle body with a seafoamed intake. I'm going broke chasing sensors......I'm obsessed with changing the cps, but have thought about o2 sensors also. They are about 1 1/2 years old. Long winded, but you've got the details.

Thanks in advance

Year, engine, mileage? The more you give the more others can help you.

So if i'm understanding this correctly, your Jeep just sits there and cranks and cranks and cranks unless you give it some gas? Once it gets running, how is the idle?

I had a similar problem not too long ago on my 99 where it would get these fits where it didn't want to run. It would sit there and crank all day long but never fire, unless I gave it some gas...and I had to keep giving it gas until it got warmed up or I drove it a couple of miles. Once this happened, it would idle a little rough at first, but then smooth out and never do it again until some other random time. A new TPS solved this, but it sounds like you've replaced yours twice?

It's a 99 4.0 with 125000 or so miles. It will turn over, start, then immediately try to "choke out". I usually turn it off and re-crank it. With just a little gas as I turn the key, I'm fine. TPS is maybe a week old. As soon as I cranks it runs smoothe with no jerks or anything strange. It's only when it starts. On a side note, I did remove my K&N and put the stock airbox back on, with a couple extra holes, but this was happening before I did this.

bad cell in the Batt.. or other elec prob- ie: alt
injectors only work properly at the right psi when the batt gives out thats the first thing to suffer..
had to hold my foot on the accelrator to crank mine for a few days till the batt completely crapped-out, after a few mins of running/driving/accelerating/ giving gas, it would straighten out, charge from the alt would raise the battery back to normal..

I wondered about the battery and alternator...Do you think an Advance/AutoZone check will work just as well as an alternator shop for testing it?