Civic b20b 16a swap coolant issue

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Hello I'm fairly new to this forum but I recently got my hands on a civic with a b20b 16a swap starts up and runs pretty good but I have a couple of issues, the rad fan never seems to turn on, I noticed this when I had it idling and coolant started to boil out of the overflow, I checked the fuse box but noticed there wasn't a fuse in the fan relay so I swapped the rear defrost fuse to see if that worked but didnt...not sure if it's specific or not? I'm kinda new to this whole engine so I don't want to sound like an idiot but if feel that's long past. Anyway when I am driving it always wants to die when I go from say 3rd gear to neutral when I'm trying to stop. Need help diagnosing these issues also I checked the oil and radiator and both are clean with no contaminants so I ruled out the head gasket, would appreciate any input!
well A the fans need to turn off , its with a temp sensor and a relay and deff has a fuse but you can come up with your own deal if needed and B gotta make sure (if understanding right b16 head on b20 block ?) that they did the conversion correctly
I guess I can add pictures and a video lol. What they said is it was a built b20 block and a 16 head, it just confused me because it looked like either they wanted to run a switch to the fan or just forgot to replace the fuse, if the relay even works. Either way I'm pretty lost
I mean you bought it like that ? neverrrr buy somebody elses problem car no telling but yea add some pictures
Yeah, I can't even fathom why I did that...but I'm here now and I have faith in this, when I had it moving she really wanted to go but I havent registered yet so I haven't tried to push it
Also I traded it for my beater, in terms of the beater I only put in $300 buying and fixing it...realistically I'm on the fence about it
The knocking you hear when I start it up is just some plastic that's loose, concerned me the first time I heard it until I figured it out lol
Check Engine Light should come on when key goes to "on " position. It seems like the bulb is out or they unhooked it. You could have an engine code.

You bought a possibly issue riddled car. Hard to say.

What ECU is in there? Does it have a port (aka female plug that a printer cable can plug into)? If so, you might be able to check engine codes.

Engine doesn't seem to Rev right but idles like mechanical timing is good.
Where is the ecu is it located under the passenger carpet? And when I reved it I lightly tapped to see if it would die but it held up pretty well this time it's an odd one,
They probably built it, beat the hell out of it and wanted to get rid of it, thing is it wants to go, I'm just worried about driving it again if anything resides as an issue
meh that tells us nothing about the quality of the tune, and I want things like knock sensor (for timing advance/retard ) the ecu makes adjustments with the O2 sensor, and dumb unless wide band is in its place , same note the ecu has nothing to do with your cooling issue but the car should pull nice if its running right
Sorry again, this is like a brand new realm of confusion to me I'm going to take it out for a spin soon, if it doesn't die that's a step forward...and if it doesn't have its coolant issue with it boiling out the overflow (temp gague never went past half) then I feel golden, oddly enough the problems seem to fix themselves...
Coolant fan turns on? Thermostat opens and coolant flows when it opens? I'm betting the fan isn't turning on. Jerry Rigg University could be an issue with your swap. Really hard to tell through the Internet.

Electrical timing is where right now?

I've never seen so many sensors deleted!!

I don't know why people want O2 disabled. It has an important place when it comes to basic things like helping monitor and keep air/fuel ratios in an acceptable realm.

Knock sensor delete? Not a big deal. I've seen a GSR swapped EG with knock unhooked on a stock ECU. He drove it daily. He still turned 13.5's with I/H/E and 22" slicks.....all day. I seen him run 20+ times.

It's hard to help you fix this via internet. We can give advise but most advise will based on something to change.....$$$ and I'd hate to tell you to do things that cost money but may not solve the issue.