Intermittent High Idle

[Blackout67]

Recently bought a 96 1500 with the 350 Vortec. It's my first manual so I've been practicing driving. First day I took it out it was completely fine no idle issues, only problem is a slight smell of gas when I come to a stop.

When I took it out a few days later, after driving it for about 30 minutes while sitting at idle speed, the engine speed would slowly ramp up to 2k. It happens only in neutral or with the clutch pressed it or atleast that's the only time I've noticed. Blipping the gas doesn't work like on my old blazer and the only way to stop it is to shut the engine off and turn it back on, then some time later at seemingly random it'll happen again then go away randomly some time later, so im sure it isnt a vacuum leak or it would be a constant high idle right?

I'm guessing it's either the CPS or TPS, but I want to diagnose it before I throw parts at it. Has no engine codes or lights on the dash. Also, it seems the temp gauge only goes up to about half of normal operation temp (about 1/4 on the dial), and I heard someone replaced the temp control sensor and that helped with his idle issue? But I have the issue at cold start and when it's fully warmed up as well, so I'm not sure

 

[OBS_Trash]

Your gauge could be reading different from the VCM is getting. Your dash temp gauge and the Ctemp sensor are 2 different items. The dash gauge element is on the driver side under exhaust manifold between C1 and C3 spark plugs. The CT Sensor for VCM is on the front of engine left of EGR Valve.

 

[Blackout67]

Your gauge could be reading different from the VCM is getting. Your dash temp gauge and the Ctemp sensor are 2 different items. The dash gauge element is on the driver side under exhaust manifold between C1 and C3 spark plugs. The CT Sensor for VCM is on the front of engine left of EGR Valve.

Noted. I will have to check that out when I get off work. Does it usually get gunked up and need to be cleaned?