From a stop it'll take off but once it gets up to in rpm it slips like if it were in neutral. Also from any gear it seems to move but not like before,but as soon as it get to about 3k in the rpm it just breaks up and redlines. Could this be the converter or is it the entire trans?
Sorry, but I don't have the experience to answer this.
But the experts probably would want to know if this happens in all gears or just in one particular gear.
One particular gear indicates a transmission (or tuning) problem specific to that gear.
Slipping in all gears could be caused by a defective forward spag, forward clutch, forward accumulator (in the valve body), low line pressure, low trans fluid level or a bad converter. (I know nuszing about converters.)
Therefore post more details and hopefully an expert can give you a better answer.
Important to know if u are loosing line pressure....gauge port is on drivers' side above shift-linkage. 10mm socket to remove the plug and hook up a 300psi gauge. Drive and replicate problem...did pressure fall off? If so...Worn output shaft bushing, pump stator bushings (for the input drum), and at speed any imbalance (made worse by beast sunshell) can cause a pressure leak resulting in a no drive condition until u back off the throttle and/or slow down. Last one I had do it was a 94 chev truck (non-pwm 4l60) and it would "nuetral-out" at 75mph or so. Rear bushing at the stator support, and rear case bushing should tighten it up, but if your in there....do it all. If it maintained pressure, it could be forward or 3/4 pack.
I will try to make a video and hopefully that will make it a little bit easier.
Try to obtain a 300psi oil pressure gauge, I run my line up the front fender w/ blue tape and place the gauge on the windshield onder the wiper so I can read it and still see the road. It ain't pretty, but it's a TEST drive
One of the most common issues with the 4L60E is the 3/4 Clutch failure, when that happens you will have a solid 1-2 shift, but then where the 2-3 shift should be you will instead get a netural like condition when accelerating, but when light on the throttle it may either somewhat hold 3rd gear (depending on how bad it is burnt up), but it will always have 2nd gear at lower throttle. On another note the band is used only for 2ND and 4TH Gear, so if there was a issue with the band you would have a slip on the 1-2 Shift, and 2nd not holding very good or at all depending on the condition. The 3/4 Clutch is used for 3RD and 4TH gear.
The previous post #14 answers you fully. Your 3/4 clutch is worn out and your trans needs a rebuild.
How much would an average rebuild cost? Isn't it just better to buy a beefed up 4l60e ie from like RPM or a th400. I'm just wondering because I keep hearing horror stories of rebuilds breaking very soon after being rebuilt and not even being worth it.