01 Explorer idle drops to 0 when in drive

My 01 explorer shudders and dies while in drive when I have to slow down to a stop. The rpms drops all the way to 0 and the car dies. I can put it in N or park and it starts right back up, put it in drive and it dies again. In the past 3 wks I have been stranded or barely made it to the shop. The mechanic suggested full tune-up, fuel filter fuel line change, and raised the idle. It ran fine for about 10 days, then started again. I took it back and he suggested I have the idle switch changed, transmission serviced. I got it back today and went less than 10 miles, parked, on my way home it started again. The mechanic does not seem to know what is causing the problem. I don’t want to think he’s ripping me off because everything he has done was need, but I have spent over $700 for this one problem. Please help me before I have to spend another $400 on work that doesn’t fix them problem. The truck has 89k miles.

Peabodpewt, try this … I guess this is an automatic and the problem could lie in the TCC torque converter clutch,which in other words is the lockup for the overdrive or 4th gear of the transmission. It sounds like it is not dis-engaging by your symtoms. A simple test would be to unplug this connection at the transmission. I do believe it is located on the side of the transmission. But first disconnect the battery and then unplug the connection. Now reconnect the battery and start the suv. Let it idle in park for 10 minutes for the computer to relearn its perimeters. Take it for a test drive . If this is the problem area it would not shudder and stall now because the TCC solenoid is not plugged in. Can you drive a vehicle this way,sure you can but you will have a higher rpm at highway speed,meaning lesser gas mileage because you would no longer get the lock up of that 4th gear in your automatic transmission. Well how to fix this if this is the problem area,a new TCC solenoid…keep your fingers crossed that is all it is,otherwise more indept electrical diagnosis will be needed to find why it is cutting off like a reference signal…possibly a crank sensor would be my second test.

Is the idle normal in park? Then it is likely the transmission. If not it may be the Idle Air Control valve. Was that your idle switch you mentioned.

There is no way to increase your idle. The throttle can be opened more, but the IAC should reduce it. Cleaning a dirty throttle body will increase the upper range of the IAC.

My 2000 Explorer started doing this some 12K miles after I had done a tune-up. But, I ruled out ignition problems, because One: the CEL light was not on, and Two: when it was running, the power was smooth and even. I also ruled out the torque converter, because it was not jerking when put into drive, but just seemed like the engine could not adjust fast enough to the change in load from neutral to drive. When we were on the street and came to a stop, it seemed to struggle sometimes before finding the right idle again.

What I did was get a bottle of Techron fuel system cleaner, gassed up with mid-grade, and took a 60 mile trip around Atlanta’s I-285 perimeter highway at 65 MPH. I figured that it was carbon build-up, sludge, or dirty injectors. Either way, that cleared-up the problem, and it hasn’t returned. And this was a year ago.

BTW, I have the 4.0L SOHC V6 with the towing package.