I have a 2000' Grand Cherokee, 4.0L with about 100k miles. I replaced a bad starter about a year ago among other things like water pump etc.

About 6 months ago every now and then when I start it it dies about 1-2 secs later, when i restart it I have to throttle it up a decent amount to keep it running. After a few seconds at a decent idle (2000 rpm+) it will stay running and idle back at normal. Sometimes I cant get it to start at all, Ill wait a few mins and try again and it will start, but I have to throttle it up for a few to keep it running.
It does NOT do this every time. sometimes it will start and be fine. I haven't a clue what it could be. I have cleaned the MAP, checked the coils and plugs, Fuel pump seems to be ok. Trying to find the solution, I saw something about the Crankshaft position sensor. However, the symptoms dont quite fit.

Has anyone had the same problem?
Any help is appreciated, Thank you

 

When you cleaned the MAP, did you clean the Air Idle Control as well?

 

I cleaned the IAC as well, There was some carbon build up on both, but not bad at all. I know on my Chevy with a K&N air filter the oil can and has caused problems in the MAP. I plan this weekend to Clean both again with a little more care and cleanliness.
If I have time I probably will change the plugs and test both the Cam and Crank position sensors.
I am not a mechanic, well I guess I am the "family" mechanic, and I did some reading last night. Would a faulty TPS cause these symptoms? I get no codes to read from OBD, and like I said it doesn't do this every or all the time. There is no pattern to the madness that I can see.
I have done good old Honda timing belt replacements, engine rebuilds etc, so feel free to hit me with tests to do that you might think will help diagnose this deal. The wife drives it 99% of the time so I dont need her and kids broke down.

Thanks again.

 

My wifes 97 zj 4.0 does the same thing so if you find any answers let me know, or if I find out something I will let you know... this weekend I am gon check the distribitor cap and rotor and mayb replace the crankshaft position sensor.