Engine races when in drive before it kicks into gear - '95 Disco

[DiscoDolly]

I'm a little hesitant since I'm not very proficient with this stuff, but I'm going to put this out there. If anyone can help guide me, I'll be sure to add more specifics as I learn them.

As long as I've owned it (3 years) vehicle has always "knocked" loudly when I shift into reverse. Well, at least 1 out of 4 times. The newest development is that the engine races when I'm in drive. It will jump up to 3,000+ rpms with just the slightest amount of gas (for instance, 15 mph). For now, it seems to shift into gear after driving slowly for a short while but I'm concerned that there is a much larger issue at hand.

Can anyone post suggestions on what I should be looking for to provide this thread with more details? It's an automatic transmission.

 

[Disco Mike]

So when was the last time you cleaned your t/body and IAC? Have you changed or checked the ATF level and checked the fluid for color and burned smell? When was the last time you greased your u-joints? How many miles on the engine?
You have probably damaged something since this has been going on for 3 years.
That being said, when was the last time you did a major service on your truck?

1 Oil filter, K&N 3001 or Mobil 1- 301
1 Factory air filter
6 Qts. of engine oil
2 feet of 3/16th vacuum tube
2 feet of 5/16th vacuum tube
6 Qts. Of Vavoline’s high mileage Dextron 3 ATF
7 Qts. of 80/90W synthetic gear oil, 85W/140 for HD use
3 Pints of Vavoline’s DOT 4 Brake fluid
4 Qts of synthetic ATF fluid
1 bottle of Lucas P/S stop leak
1 bottle Lucas Tranny Stop Leak
2 Gallons of Peak or any green or yellow coolant, don’t use Dexcool
1 Bottle of Lucas Power Steering additive
1 Bottle of Lucas Transmission additive
1 Can of Spray Carb. Spray
1 Can Of Brake cleaner
8 Spark Plugs, I use Bosch Platinum Plus 4's
1 Set of Magnacor or STI 8mm plug wires
1 Serpentine belt
2 Bottles of SeaFoam gas additive
1 T/Stat
1 bottle of WaterWetter or Purple Ice
1 new fuel filter
Hoses and belts, as necessary
Front and rear wheel bearings and all seals for wheel bearings and swivels if necessary

60,000 Mile Service or Major Service for High Mileage Used Vehicle just purchased

Bleed the brakes
Flush and change the power steering fluid adding one bottle of additive
Service the tranny adding one bottle of additive, change the filter if necessary
Change the coolant and t/stat
Do an engine flush before changing the oil
Do an induction cleaning
Clean the throttle body
Add fuel additive to full gas tank
Change both of the diffs fluid
Change the t/case oil
Replace the plugs and wires
Replace the air filter
Lube all the drive shaft grease fitting including the 2 slip shafts
Do full inspection of brakes, hoses, bushings etc.
Repack or replace the 4 wheel bearings
Service the swivel balls, reseal, refill and adjust the pre-load
Replace the fuel filter
Inspect and replace all hoses, brake, coolant and cooler lines as necessary

 

[DiscoDolly]

Thanks Mike. I "purchased" it with 150K on the engine, and now have 162K, 3 years later (Full disclosure - I traded a mountain bike for this vehicle and have no real knowledge of the service history.).

After checking the ATF, it looks like my first step is to drain and add. It's definitely low.

Do you have a step-by-step, specific to the Disco1? It is a '95. I'm finding a few how-tos on the internet, but I'm not sure they are specific to the D1. Am I best to bring it into a shop? I've got one a few miles away, but I'm a bit nervous driving it at this rate, given how low the fluid is.

As for a major service, I think it's been awhile. I brought it into a shop several times before driving from CO to IL 2 months ago. I asked them to do a thorough diagnostic and this never came up.

 

[Disco Mike]

You better learn to start your own work or you will go broke. That service will cost you an easy $1000 at a shop. If you want some help with it, PM me your number and walk you thru it.
Also, replace your tranny filter