trying to set up a tango 40 seem to get some type of interference when i throttle down the rudder and elevator go haywire with no control if i throttle up i get control back any ideas?

check for any metal to metal contact at any point on the aircraft that could vibrate. This causes any rx to go crazy. Cuses rf interferance to enter the seystem.

Make sure your crystal is fully seated and all electrical connections are fully plugged in. Vibration will show bad connections.

well 1 day 2 planes 2 different channels first plane has had no problems since first flight started going eraccit second plane took brand new arf the tango as mentioned get the bug worked out did range testing flew fine for a few minutes and then went crazy. don't understand it

A capital letter to start a sentence, and a period to indicate the end of the sentence would help us understand your question a bit better.

Is your trouble in the air, or on the ground?

Don.

Sorry about that [8D]
Well 1 day 2 planes with 2 different channels. The first plane has had no problems since first flight. Today in flight it started going crazy. Doing twist,inverted fight then it settled down so I cut back throttle to try and land, but it went crazy again. A couple of hours later the second plane which was a brand new arf,the tango as mentioned got the bug worked out did range testing flew fine for a few minutes and then went crazy. don't understand it what was wrong. Noone else flys around me so I don't think it was another raido. Any ideas?

What is the charge on your batteries, both aircraft and transmitter?

If it is the same transmitter on both planes and the batteries are in good shape it is possible to get radio intereference from a number of sources, not only rc transmitters.
For example, I found out the other day (the hard way) that a police radio tower near the field will interfere with channel 11 & 12 on occasion.
And just because you can't see someone else with an rc transmitter doesn't mean someone in his back yard somewhere isn't causing the problem. The range on most transmitters and be up to a couple of miles.

It could be an internal TX problem if you are using the same TX for both airplanes. In that case I'd send in the SYSTEM for evaluation with a DETAILED explainations of what is happening.

What transmitter are you using?

Also;

How is your throttle hooked up to the throttle servo?

Is the metal throttle horn ( the one on the carb ) hooked to a metal clevis?
In turn is the metal clevis hooked to a metal rod?

If so put in a plastic clevis.

The throttle rod is a great source of RF noise.

-

I've had a couple of "bad" Hitec servos that would go nuts at certain throttle settings.

At first I thought I had a bad RF noise problem, coming from the engine.

I move the servo to another channel/surface, and the problem travelled with the servo.

I replaced the bad servos with two IDENTICAL Hitecs, and changed NOTHING else. The problem went away.

I've tested the bad servos on another airframe with identical results. I sent them back for exchange, and the replacements work fine.

So it is possible that you have a couple of servos that are problematic.