B20z swap done now having few issues

Well this my first post have owned two DA but just never used my account or got on here. To start of recently bought a 1990 ls auto with blown motor. Super clean interior decent body for $125. I got a hold of a b20z with a sunken valve. Used my old b18a head, dist and kept the b20 cams. Got the motor in started up all is good. Went for a drive runs good plenty of power felt like it should. Car warmed up started to drive up a hill and lost power put to the floor and car slowed to stop still flooring no brakes and was just sitting there car at around 400-800rpms. Backed down went on different street to avoid hill put to floor block later got to 20-25mph and power came back. It does this also sometimes when I come to a stop and real sluggish to take off. I don’t notice any misfire. The only thing is that I did not yet plug in the sensors on back of motor because I don’t have any to install. (Friend took old motor in for a core before I got them off) I was going to take off the IACV and clean it soon as rain stops. Does anyone else have an idea what it could be?

fuel filter maby

forgot to mention drained tank and put fresh fuel and filter on before starting.

what comp u useing b18a1 ?

yes using factory ecu

timing?

belt is good marks all line up and distributor set right with timing light.

have u checked the fuel prssure

fuel pressure good. Took for a short drive yesterday. Wasnt as bad but still huge power loss on take off.

The only thing is that I did not yet plug in the sensors on back of motor because I don’t have any to install

That could be your problem, what sensors are you talking about specifically?

Its just a coolant sensor for the fan I believe.

That could very well be it. Engine Coolant Temperatures (ect) rise, and cause the ecu to retard timing to keep the heat down, possibly even go in to limp mode. You shouldn’t even be starting this motor without the sensors imho.

agree bump

ninezeroteg is right and it sounds like its going into limp mode so wait until you have all the sensors to run the motor again

It sounds like you are talking about the ECT switch, which was relocated to the thermostat housing on the b20 from the back of the block. You need to use the b20 thermostat housing and extent the wires from the plug. I don’t think that would be your problem though as it goes to the fan controller. I am guessing you also didn’t install the oil temp switch, but that also goes to the fan controller.