94 3100 with 208000 miles woes

[z26runner]

Hello, I am a new member to this site. I have been around for quite some time though. I was on bstuff for many years. I thought I had an account on here, but I quess I was wrong. Well, this is my official hello fellow retta owners!! Ok, now time to get to business. I have a couple questions for you all. First, I need to know what the rail is called that comes from the coolant tank to the front of the motor. It is a .125 dia rail that has seen better days. I want to know if there is a name before I run to find the part around town. Second, I have a SES light issue that is happening recently. The situation: While driving the car will act as if I stopped giving it gas but does not die or studder from what I can tell. When this happens it lasts a few seconds, then it comes back and good to go. After it does this hiccup the light comes on. The strange thing is the car runs awesome even with the light on. Guages are where they need to be, and no abnormal sounds are taking place. I hope this gives some insight on my situations. Thanks in advance for the help. I am not online as too much so responses might be delayed. Today, is my typical work on all vehicles day, so I will check in from time to time.

[3X00-Modified]

That pipe is the heater core bypass line. As far as the studder while driving it sounds like you may have a fuel pressure issue, or an ignition issue. Mostly likely ignition since it throws a SES light, but since you have not pulled the code all we can do is guess. The light on typically just means something "happened" and you need to pull that code to find out, it doesn't always mean something is malfunctioning right that second.