3 problems related?

2000 se with a 3.1. The original motor developed a knock at 191k. Replaced it with a boneyard motor with 93k on it. I used the egr, iac, plugs, wires off my old motor.#1. Occasionally it will throw a code for multiple cylinder misfire, but more often it is cylinder 3 misfire. Engine surges or stumbles at full throttle but sometimes it will run fine. It doesn't always throw a code when it does this. #2. When you start it it revs up a little over 2000 rpm and then settles down to regular idle, it does this hot or cold. #3. When driving at highway speeds, roughly 45 to 75 mph, the engine seems to cut out when accelerating slowly or going up an incline. Once the tranny downshifts it runs fine. It just kind of bucks and kicks almost like the tranny is slipping and catching. Which is what I thought it was until I watched the tach. Instead of revving higher it actually drops about 200 rpm or so. Any ideas?

Try a tune up first. I wouldn't re-use old parts from a knocking engine. The best way to know that the new engine is good is to start it off with at least a fresh tune-up, filters, and of course oil. Re-using the EGR isn't a big deal, but if it was the original one with 200k on it, I think I would have changed it and both of the oxygen sensors.

I'd start with new plugs and wires. Willing to bet one of the wires is bad.

the slipping problem is more than likely your lock-up torque convertor. Try disconnecting the plug on the transmission and see if it goes away. If it does, it should be a purple wire in that harness that needs to be removed by slipping it out of the plug.

the slipping problem is more than likely your lock-up torque convertor. Try disconnecting the plug on the transmission and see if it goes away. If it does, it should be a purple wire in that harness that needs to be removed by slipping it out of the plug.

Are you suggesting that he disconnect the 20 way connector and test it? If you disconnect the 20 way electrical connector on a 4T65E tranny it is all going to go away. There is no separate TCC plug independent of the main data input from the PCM and 12v supply circuits.

Pin U which is TCC release from the PCM the wire is color coded yellow. And Pin T which is ground signal from PCM to TCC/PWM solenoid is brown. The wiring color coding varies with year and model Grand Prix, however, the Pin configuration is correct.

I agree with the others. Do the basic stuff first.

All these problems started after the engine swap. I used some of the older parts because they are known to be good. Other than the knock it ran great before.The plugs and wires had about 20k on them. The IAC was bad on the new motor.

it may be a different color. I had the same problem with my 95. I don't have the vehicle anymore however it definetly sounds like the same problem.

it may be a different color. I had the same problem with my 95. I don't have the vehicle anymore however it definetly sounds like the same problem.

Your '95 had a 4T60. The '97 - '03 GPs have a 4T65E. The wiring harness is totally different. Different beast.

Possibly a similar problem but to inhibit the circuit the approach is different. I provided the pin numbers and wiring color coding if that needs to be done for troubleshooting purposes. But simply disconnecting a wire may not be a proper permanent fix. Other components valve body related and solenoids such as TCC-PWM could cause torque convertor problems in a 4T65E tranny. The PCM could cause it. A mifire can appear to be a torque convertor or tranny problem.

Torque convertor lock/unlock is beneficial for fuel economy and I would not permanently disable it.