I have a 98 4 cyl. During the spring and summer, it would start up fine and run OK. Now that it is getting cooler at night, starting it up in the morning and keeping it running is now a problem,. It did this last fall/winter too. Once the ambient temperature gets up around 60 - 70, such as when I leave work, all the problems go away.

I think, as old as this truck is, it probably has a number of things that need replacing. I replaced the cap and rotor and the coil. Cap and rotor were wasted. I did the coil just because I was there.

I replaced the TPS sensor yesterday, which helped as it went to high idle and then came back down, which it has never done since I've had the truck. I was hoping I had fixed my problem, but this morning, it took a try or two to get started, and I drove to the gas station and it quit when I pulled up to the pump. This was a little different behavior then before, as before it seemed to flood out (smell gas). I have a code reader, but didn't have it at the time to clear the codes yesterday. I cleared them this morning. I will have to wait until tomorrow morning as it is now warm enough outside for the problem to not show up.

Ok, after all that, I assume that the 4 cyl engines only have two O2 sensors on one bank obviously. My understanding is that the O2 sensors don't affect engine operation until the engine is up to operating temperature. If this is true, then I don't need to consider them as a part of my cold engine start problem, correct?

Any advice would be appreciated.

 

Ok

My 98 2.5 has never had this problem but I would start with a full throttle body cleaning the idle chamber is probably all mucked up one thing I would do also is remove the Air Temperature Sensor and clean it or replace it.

I would then check all your vacuum lines half of my lines were close to rotted off and cracked up especially look at the vacuum lines coming off just below the throttle body that is where they rot the most because they get coated with oil that rots them quicker.

How are your sparkplugs?

I have a few more but that’s a start

A vid on cleaning the 2.5 throttle body this guy is a spaz or high on caffeine or just a nervous nut but this vid is ok

 

Off topic a bit but this is how you can get the 2.5L engine to sound.

Beware this guy is a little off in the head but worth listening to remember it is the 2.5L engine same as yours

Vid is very dark and out of focus but watch the complete thing