5.0 litre 97 explorer idles @ 2000 rpm after -0 start w/ether. already rr maf sensor, brought it down from 3000rpm to 2. I have no diag eqp mech told me it was the prob from the ether

check the map sensor. If you unplug it and notice no difference, then it is your maf sensor.

I'm guessing but this sounds like air problems. do you have a new air filter? The O2 sensor may be off but not technically bad yet. I'm pretty much stuck on something restricting the air flow.

Check the fuel pump output. Some will work but not have enough output for the instances you describe. Find a place that can test the fuel pump pressure.

You can try cleaning it first with some sensor cleaner, usually works well. Any trouble codes?

Go to www.hmaservice.com and register your vehicle by VIN #..
you'll then have access to wiring diagrams, shop manuals,
service bulletins, illustrations, etc. To diagnose a 2000 or 2001 1.5L Accent Diagnostic Trouble Code (DTC) P1128 (FUEL SYSTEM LEAN -- PART LOAD), check the following:

• Check the intake system for air leaks.
• Check that the Mass Air Flow (MAF) Sensor (P/N 28164-22610) operation meets the specifications listed below. If the MAF sensor output is significantly lower than the reference value (10% or more), then replace the MAF sensor.

Table 1: Using the Hi-Scan Pro in the Hyundai Diagnostic Menus Current Data Screen TPS (%) 0
3.5
5.1
7.4
MAF (kg/h) 10
21
30
47
RPM IDLE
2000
3000
4000
Table 2: Using the Hi-Scan Pro in the OBD-II Menus Current Data Screen TPS (%) 0
3.5
5.1
7.4
MAF (g/h) 2.8
6
8.5
12.7
RPM IDLE
2000
3000
4000

WITH MANUAL TRANSMISSION

Table 3: Using the Hi-Scan Pro in the Hyundai Diagnostic Menus Current Data Screen TPS (%) 0
2.4
3.9
5.9
MAF (kg/h) 9.5
19.4
28.8
43
RPM IDLE
2000
3000
4000
Table 4: Using the Hi-Scan Pro in the OBD-II Menus Current Data Screen TPS (%) 0
2.4
3.9
5.9
MAF (g/h) 2.5
5.5
8
12
RPM IDLE
2000
3000
4000

Hello and welcome to FixYa!

If the check engine light is on then there's definitely a problem. The engine rpm is erratic right? This can be caused by a faulty MAF (mass air flow) sensor. If the MAF sensor is faulty the idle will surely be erratic and may cause stalling.

You will need to have it replaced to make the vehicle back to it's normal operation again.

Hope this helps and thank you for using FixYa! Have a good one!

The p1140/121 code indicates the MAF was not as expected compared with values from IAT, TPS, CTS, IAC command, and RPM. Meaning all THOSE sensors and the IAC solenoid position data have to be working and in normal range for the MAF to test normal and not code. Further, any vacuum leaks will ruin the MAFs accuracy when compared to the others, as will a PCV/CCV problem.
If you lobbed a MAF at it already...you have already done the least likely and most expensive part. You really need to look at data and see what the DME sees. Is throttle showing closed at idle, is air temp normal? Is RPM under 725 idling, does it flare idle up and down in 10 seconds. is there any vacuum leakage anywhere? even a small amount can make a code level of difference?. Intakes leak a fair amount. CCV valves much more likely to leak, as are the hoses to it. TPSs dont fail that often but can. IACs usually code when they fail...but they could plug up and not code but have improper air bypass that affects the MAF reading. Throttle cables/adjustment is critical...keep that high on priority list.
iATN Tech.

Maybe a short to the TPS or something shorting it out. There's also the IAC that really controls the idle but usually it will cause the RPM's to go up and down a little erratic if bad. The MAF sensor can cause major problems as well but since you already swapped the TPS and it helped and then stopped I would focus on that sensor and especially it's wiring to and from the ECM. Be careful with the sensor signal wire to the ECM can blow it if more than 5v passes or spikes.

check the oxygen idler sensor