remote start rpm fluctuate w heat

Just did a 2002 Silverado with an Ultra Start last week.  It was a 1500 with the 5.3L V8.  No issues with idle during remote start. 

I did run in Tach Mode and connected to a F.I. wire :

There is a connector at the back of the fuse box that has all of the controlled ignition wires.

I also split the U1272s'  two Red +12V constant wires between the trucks Red and RED / White +12V constant wires shown below.  On the 2003 they might both be Red.

Extra relay wiring :

Relay Pin 86 and Pin 87 to +12v constant thru 20A fuse.

Due to the gauge of the trucks ignition wires, I felt it prudent to split the U1272's load between the two available +12v source wires.  The additional relay for ACC2 was connected to the same source wire as the U1272's Red wire that supplies the starter output.

As for the Brown ACC2 wire, there is another post, https://www.the12volt.com/installbay/forum_posts.asp~TID~128550~PN~1, that suggests that it might have something to do with the O2 sensors.  That could affect idle quality.  I usually try to duplicate with the remote starter exactly what a key start does.

The U1272's Blue antenna lights blinking when locked is a nice feature.  It gives the impression of an alarm system and some extra peace of mind.  It is user programmable.  See Menu 3, Item 7, Opt 1 if you don't want the blinks while locked.

Keeping the wire inside the vehicle and out of the engine compartment has its' advantages.  I believe on your model year, you can pop out the vent / parking light control assy at the left of the instrument panel and locate the White Tach wire in a group of wires with some gray tape on them.  Should be the only white wire there but verify with a Digital Multi Meter.  Jim H does  plenty of these trucks and can explain better...