98 1500 - This Truck - Replaced fuel pump early September (for another issue) and thought the problem went away. It did not.

Truck starts and immediately dies if you don't give it a little gas. Once it's running, I have to keep just a little pressure on the gas and keep the RPM around 900 for a minute or two, then slowly ease off it. If it bogs down, increase pressure/RPM, then ease off again until it's idling smoothly somewhere between 500-700 RPM. If I wait a while, I can put it in gear and go no problem. If I'm in a hurry and can't wait for it to warm up, I have to drive 2-footed for a few blocks because the first time I stop, it'll die if I don't keep the RPM up. Either way, once it's warmed up it runs fine and will start fine the rest of the day.

Someone told me a crank sensor. And I have vague memories of helping a friend replace a magnetic throttle positioning sensor for a similar problem 20 some odd years ago. What do you guys think? What should I be testing before I start throwing money at the problem?

 

Start with cleaning the throttle body. It likes to gunk up, and chokes the IAC passage. That's what controls your idle.

 

What condition is the battery in? If it's weak it can cause the same issue.

 

The battery is in solid condition. I haven't put a multimeter on it but, nothing about the operation of the vehicle has led me to believe the battery might be weak or failing. I'm going to clean the throttle body next weekend as suggested by HeyYou. I'll double check the battery when I do that. I might as well check if the plenum plate has already been replaced and consider doing that while I'm at it

 

Have it load tested. If it's near 5 years old it may be towards the end of it's life.