Surging/lurking in first gear?

[Bronconnoisseur]

I’ve noticed that in first gear, whether it’s in 4x4 or not, there’s a pulsating surge at times at very low speeds...like when I’m just crawling through residential streets in the snow is when it is most pronounced so I don’t know if that’s related but yep only first gear it’ll surge 1000rpm and pulsate back and forth up to like 1200-1400 and back to 1000 as many times as I let it

 

[miesk5]

Yo Bronconnoisseur,
Pull the vacuum line off the mod. If fluid comes out of the vacuum line your modulator is no good.
Check vacuum line to modulator from engine intake manifold source.
See Vacuum Gauge Diagnosis - BEST!; Normal engine; Steady gauge 18"-20" at all speeds..." READ MUCH MORE
Source: by Craig U @ Reading your vacuum gauge

Vacuum Modulator; The vacuum modulator is a vital component of an automatic transmission. It tells the transmission what kind of load is being put on it allowing the transmission to react with the proper line pressures and shift points. Over time, modulators can develop leaks, get ruptured diaphragms, get bent, etc. Not only can this cause annoying drivability issues, it can lead to premature transmission failure.
Inspect vacuum modulator, and it's vacuum hose back to intake manifold for leaks, etc.
It's at rear of C6, passenger side..

 

[Bronconnoisseur]

Yo Bronconnoisseur,
Pull the vacuum line off the mod. If fluid comes out of the vacuum line your modulator is no good.
Check vacuum line to modulator from engine intake manifold source.
See Vacuum Gauge Diagnosis - BEST!; Normal engine; Steady gauge 18"-20" at all speeds..." READ MUCH MORE
Source: by Craig U @ Reading your vacuum gauge

Vacuum Modulator; The vacuum modulator is a vital component of an automatic transmission. It tells the transmission what kind of load is being put on it allowing the transmission to react with the proper line pressures and shift points. Over time, modulators can develop leaks, get ruptured diaphragms, get bent, etc. Not only can this cause annoying drivability issues, it can lead to premature transmission failure.
Inspect vacuum modulator, and it's vacuum hose back to intake manifold for leaks, etc.
It's at rear of C6, passenger side..


View attachment 21985

I joined this site hoping someone like you would exist miesk5...I’ll post an update mid next week

 

[dbmcd]

IAC needs cleaning or replacement. That's Idle Air Control valve.

 

[Bronconnoisseur]

IAC needs cleaning or replacement. That's Idle Air Control valve.

I will look into that. apparently the truck doesn’t have a vacuum modulator

 

[dbmcd]

IAC needs cleaning or replacement. That's Idle Air Control valve.

Sometimes called the AIC, it regulates the idle speed for instance when the A/C comes on. When it gets dirty and sticks you can get high idle speeds.

 

[sinker4]

My 95 would start then stall. On the second attempt it would start and run rough for a few seconds then smooth out as it warmed up. I replaced the original Idle Air Control valve and the problem went away