Dude!!!!!!!!!!!!!!!!!!!
So, which ecu was chipped p28?
We can't really help you Man. First off, if the ecu was chipped you would have to convert to obd1, so did you convert to obd1?
If you are obd1, you can pull the codes by the service plug and read it and tell us what it is.
A little history about your car would be nice too. Like, when you swap the b16 did you have this issue? or this issue just started recently. Did your car ran ok before? Things like this are important.