Before I go and mess with things that I am new at (TPS, injectors, IP), I was hoping to get some feedback to focus my search.

I took the new truck (the one in my sig.) on a 500 mile fishing trip yesterday to get used to the rig, check things out, and bring home dinner. The truck ran fine on the way up, but when we got back in the truck and started it up it began to switch back and forth between two different idles. Each lasting about 10 to 15 seconds, one smooth one rougher.

About halfway home, on the freeway, I was going up a slight slope about 65mph ready to pass a big rig when it felt like I lost the momentum I had. My first guess was that it dropped out of overdrive(?). I kept on the fuel and it jumped back into OD after a couple seconds and I got around. I noticed this a handful of times. I would give it fuel up a slight grade or passing and it would lose the momentum. I also noticed when giving it fuel and going over a rolling bump it would do the same thing (This happened 4 times).

The reason that I am speculating that it was dropping out of OD is that when I turned the OD off while driving up a slight grade 60mph it felt exactly the same. Could a faulty lift pump do this also?

Any help greatly appreciated. Thanks.

 

Your first "problem" isn't a problem at all. Was it a little cool out when you started the truck? The KSB (german for Cold Start Aid) changes the timing a bit when the intake air is below a certain temp. This is totally normal. There's also grid heaters in your intake to warm the air as well. They're electric and can cause a drop in idle when they switch on. Could have been that as well as they cycle on and off. This is what the "Wait to Start" light is for. The grids are on and warming the intake air.

Yes, you're dropping out of OD. You need to adjust your TPS or Throttle Position sensor so that you get a lower kick-down point. The procedure for that is in the sticky section. It's really quite easy. You can also install a hand operated potentiometer and avoid all that. A little more work, but worth the result I think.

 

Thanks Tuckerdee,
It was chilly, but coastal California chilly and inland chilly are two different things, as you may know. However, it did remind me of the lights dimming on my 91 when the grid heater would turn on and off after I started it and when I was waiting to start. (KSB was unplugged on the 91, so I never experienced a working KSB)

I read over the TPS sticky before I posted and looks like pretty straight forward. I just wanted to be sure before I started. I'll search up the potentiometer but will probably try the TPS adjustment to learn something.