1993 YJ 2.5 slow start and very bad idle at startup

Hello.
New to the forum, but have searched here a lot in the past.

I have searched a bunch of common threads on here but still can’t find the answer to the issue that I’m having.

I have a 1993 Jeep YJ with a 2.5L engine and the AX5 five transmission. 188,000 miles. When Jeep has been sitting for a while and I started up, it often takes a very long time to start and when it does start it idles incredibly low sputters a lot and sounds like it’s not fully running. If I give it gas, it will stall. Once left running for about 3 to 5 minutes, The RPM will stay right at 1000 and the jeep runs perfectly fine every time.
This does not depend on temperature as it did it all summer.
Once the engine is warmed up it has no trouble starting.

I have replaced the following:
New fuel pump
new fuel filter
New fuel hoses
new idle air control valve
new throttle position sensor
new crank position sensor
new map sensor
new fuel pressure regulator
new intake, air temperature sensor
new coolant temperature sensor
New Distributor, cap, rotor, wires, Plugs

No known exhaust leaks or vacuum leaks.. at least from what I can tell.

Battery starter, and alternator check out fine when tested.

CEL comes on with Key
Only codes are 12 and 55 because I use a battery disconnect sometimes.

I am stuck.
I drive it every day and I’ve never been left stranded but I would like to get this fixed. Any help would be greatly appreciated. Thank you!

Kunze4u2 said:

Hello.
New to the forum, but have searched here a lot in the past.

I have searched a bunch of common threads on here but still can’t find the answer to the issue that I’m having.

I have a 1993 Jeep YJ with a 2.5L engine and the AX5 five transmission. 188,000 miles. When Jeep has been sitting for a while and I started up, it often takes a very long time to start and when it does start it idles incredibly low sputters a lot and sounds like it’s not fully running. If I give it gas, it will stall. Once left running for about 3 to 5 minutes, The RPM will stay right at 1000 and the jeep runs perfectly fine every time.
This does not depend on temperature as it did it all summer.
Once the engine is warmed up it has no trouble starting.

I have replaced the following:
New fuel pump
new fuel filter
New fuel hoses
new idle air control valve
new throttle position sensor
new crank position sensor
new map sensor
new fuel pressure regulator
new intake, air temperature sensor
new coolant temperature sensor
New Distributor, cap, rotor, wires, Plugs

No known exhaust leaks or vacuum leaks.. at least from what I can tell.

Battery starter, and alternator check out fine when tested.

CEL comes on with Key
Only codes are 12 and 55 because I use a battery disconnect sometimes.

I am stuck.
I drive it every day and I’ve never been left stranded but I would like to get this fixed. Any help would be greatly appreciated. Thank you!
View attachment 123532

Click to expand...

Update, I just replaced the fuel pressure regulator and saw no change in the behavior. When I started up it almost seems like one of the cylinders isn’t firing incorrectly. Looking for solutions to this issue.

I appreciate of the help on this issue.
Fuel pressure was good.

Turns out it was a combination of a few things…
-New temp sensor made a difference. Tested old one and it was way out of range.
-spark plug wire #1 was loose on the cap and bounced off causing me to lose the cylinder.
-I had replaced the crank position sensor.. but the wiring after the plug had rubbed against the frame and shorted.

All together.. fixing these got it running well again!