1994 4.0 automatic, When put in gear it starts bouncing back and forth from 400 rpms to 700

[clapped4.0]

Anyone know why it does this? It just revs back and forth.

 

[rumblecloud]

Could be a few things.
Have you pulled any codes yet?

Vacuum leak
O2 Sensors
MAF sensor
And more...

Normal RPM should be anywhere from 8- 1000rpm at idle Higher at cold start-up, then down as it warms. Have you performed any maintenance prior to this happening?
What's the mileage?
Does the rpm continue to rise and fall when it's warmed up?

A cheapo OBD1 code reader from a local auto parts store could offer some clues as to what might be causing it.

Please post back with more info so we can help.

 

[clapped4.0]

only codes are for transmission 3/4 shift solenoid and torque converter clutch circuit fault. Looked for vacuum leaks and found 1 which was causing a 1500 rpm idle. replaced MAF sensor. Haven't checked o2 sensors. Previous owner had done spark plugs and coils just before I bought it and I haven't driven it much since i bought it. 210,000 miles. It seems to do it more when warmed up.

 

[clapped4.0]

Also anyone know where to find tcc solenoid at? a4ld trans, tried everywhere I could think of but not finding any.

 

[ShhhhhDougsHere]

Have you thought to test your,
Idle air control valve?

I'm adding a quote from a post in my thread
" I'm Sure I Got a Short"
that @Brain75 posted.
It's post #346 on page 24 of my thread.

thought for you on the running like crap and stalling when you come to a stop - the IAC valve can cause that - test by removing and see if it makes it worse... same means it is not working right. bench testing it can be done too
snipet out of an article:
"
If the idle air control valve is hot (50°C to 100°C), you expect a resistance value between 21.5 Ohms to 29.5 Ohms.

A cold IAC (-13°C to 50°C) is expected to have a resistance between 17 Ohms and 25 Ohms. In some car models, the resistance value goes as low as 7 Ohms.
"

How To Test Idle Air Control Valve With Multimeter (GUIDE)

If you're having problems with your idle air control valve, don't worry. We created guide about how to test idle air control valve with multimeter.

electrouniversity.com

Open the quote and you will see a link that explains the test.
I don't know what all you have tested so far but you may try this test.
And the best 2 parts about this test is,
1. It's easy to do.
2. It's free to do.

I'm just a novice around here so I'm trying to help the best way I can.

I wish you Good luck and I hope you figure out your problem and then can have some real fun with your truck.

 

[ShhhhhDougsHere]

I also just noticed that you just joined TheRangerStation last week.

I'm a little late however welcome to the family.