Cherokee running rough after heatsoak?

So I know my NSS needs to be cleaned bc after it sits over night it only fires up when I put it in neutral. The past few times I have went out wheeling my Cherokee starts up and runs just fine, but when I drive an hour+ to get to my location and shut it off it starts to act funny. After the engine is hot and has been turned off, when I start it back up it sounds like a diesel and will die if I give it gas before I let it warm back up. It sounds like a vacuum issue, but I'm curious why it only happens after it's heat soaked? Anyone have any ideas? If I start it up and let it run for a bit the diesel sound evens out and it's good to go again. I'm a little baffled by this one. Thanks for any help!

Oh and it's a 2000 XJ with a 4.0, if that matters

Heat soak leads to vapor lock. When the air/vaporized gasoline in the fuel rail clears, it runs normal again.

Tim_MN said:

Heat soak leads to vapor lock. When the air/vaporized gasoline in the fuel rail clears, it runs normal again.

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Any remedies to fix this? I am sick of leaving the cherokee running all day when I go wheeling.

This happened early on in my 2001. Took it to the dealer and they flashed some new software on the ECU. That was about 9 years ago. It still happens a little when it's over 90-degrees but originally it would trip the CEL.

BMWGuy said:

This happened early on in my 2001. Took it to the dealer and they flashed some new software on the ECU. That was about 9 years ago. It still happens a little when it's over 90-degrees but originally it would trip the CEL.

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Thanks! I'm not throwing any CELs yet

Hood vents help. So does a timer on the electric fan so it runs after shut-down.

Head gasket issue maybe...

Not a head gasket issue. Common problem. TSB says to put heat insulation on fuel injector #3. I would put insulation on all injectors and the fuel rail. There are also a few TSBs for reprogramming but that is usually for cold start issues.

Search as it has been covered many times. Another option is to rig up the fan with a timer to run after you turn it off.

Talyn said:

Not a head gasket issue. Common problem. TSB says to put heat insulation on fuel injector #3. I would put insulation on all injectors and the fuel rail. There are also a few TSBs for reprogramming but that is usually for cold start issues.

Search as it has been covered many times. Another option is to rig up the fan with a timer to run after you turn it off.

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Wow that actually helps out a lot, it never wants to start in winter when it's cold. Thanks so much!