Increased RPM while in neutral or with clutch depressed

I drive a 2001 Blazer, 2WD, 4.3L V6, manual transmission. The vehicle has 98,000 miles and has not had any major problems yet. Recently though, the engine has been increasing to about 3000 RPM if I put the car in neutral as I come to a stop. It also increases if I depress the clutch pedal as I shift gears. It will continue like this until the vehicle starts to slow down if I ride the clutch or just keep coasting in neutral (not something I do regularly, just needed to check this). The problem comes and goes, and seems to happen after I've been driving for a half hour or so, but I'm not sure if this is of any significance. Also, whether or not it is related I do not know, but I towed a heavy trailer for the first time a week or two before the engine started acting up. If anyone has any ideas what this could be, please help.

Thanks

Sounds like the idle air control valve (IAC) is sticking open a little if the Check Engine light isn't on.

Or maybe a vacuum problem

Or maybe a vacuum problem


Great point. If the brake pedal is getting hard to push down, the power brake booster may have a leaky diaphram or a cracked vacuum supply hose.

Thanks for the advice. I checked vacuums and brake components and they seem to be fine. The check engine light has not ever come on. Before the weekend, I added a fuel injector cleaner before filling with gas and the problem has since ceased. Hopefully that solves it. I will post something later if that in fact worked or if the problem returns.

Thanks again