High Idle-please help...idle's better-shifting sucks!!
 

Long time viewer, first time poster...
My blazer (2000) decided to start idling @ 2500-3000 rpm this week. I went muddin' on Saturday, and I didn't submerge it in water, but it did die on me in one big mud pit. I had a hard time starting it back, but when I did it ran fine for the next couple of days.
Now it has the high idle and shifts really strange. I've went through several different threads on here with similar issues, but so far nothing has changed it.
I have:
-cleaned MAF
-cleaned Throttle body
-checked voltage on TPS
-checked ohms on IAC

What am I not checking? PLEASE HELP!!!:icon_doh:

Take battery cable off for 15 mins, and then hook it back up.. Resets the computer.. If that don't help reply back.

Check for a vacume leak(s).

Ok, it's been giving a P0102 and P0121. I cleaned the MAF, and checked the TPS and it was showing the correct voltages. I cleaned the TBI, and removed the IAC valve to clean it. The IAC looked bad and the shaft was extended too far, so I went to advance and bought a new IAC and MAF. I just now put them both on, and the idle problem is a lot better, but the transmission is still shifting really strange. I have had the battery cable off for 15-20 minutes while installing the new parts, cleared the codes out, and I'm out of ideas. It just now showed the P0121 again. Should I replace the TPS?

I had the same problems.. replaced the IAC and cleaned the TPS..still got the high idle code. The mechanic did a smoke test and discovered a hairline crack in the intake manifold. We will replace it this week and see if that does the trick.

IT'S FIXED!!!

Thanks to another member from last year having the same problem posted on here.

The main issue was the THROTTLE POSITION SENSOR.

I don't feel it was a waste of money to replace the MAF and IAC though. I'm hoping to get better gas mileage. It has 128K on it, and those had never even been serviced.

Thank you all for the replies and for a great resourceful website.

glad to hear you got it fixed