I know there might be a few forums about the same problem but i can't find em... if someone can direct me to it that'll be great... but if not please let me know what could be the problem... i've never had this happen to me. I just got another longblock of a buddy of mine, and took my old one out. obd1 to obd1 so nothing else changed just plug and play. After changing a few stuff, water pump, timing belt, spark, dizzy ect ect... finally dropped the motor in. Gave it her first start and it started RIGHT up. fine and everything, let it warm up for a while... it idles fine, then i start to drive it and it feels like its dying but won't... im trying to take off and it takes me way too long just to get going, once i get up to about 3500-4000 rpm it starts to go normal, then shift to next gear and it either starts doing the same thing or starts bogging and jerking, but not cutting off. it ides a little above 0 likes it wants to turn off but it will not and when i rev it takes so long to past 2000 rpm and then starts to pick up a bit... im not sure what it could be, and i have not yet started to change out things or take things out without at least having a clue what it could be... well i kind of have a clue not sure but im either thinking something has to do with tps or map sensor? idk or intake manifold/TB ? if anyone has any idea what it could be and needs to changed out please let me know, thanks. Sorry for the long story....

 

sounds like your secondary butterfly is open. make sure its closed at idle

also check the timing

 

i had a similair problem, i have a 2001 gsr and i swaped for b18c type r engine and i had a really bad lag at low rpms. it was a nightmare it was going slower than my gsr and it was suppose to be an upgrade!
i took it back to the guy who swaped it for me and he had a plug in the wromg spot. it was causing bad oil pressure(so he told me) , check ur harness there might be something pluged in incoorectly, check all ur plugs on and under the intake manifold.

 

replace spark plugs, my car every month starts doing that, but im not running an o2 sensor so i think im running to rich n foul the plugs but, this is just whats happening to me so it mite be the same for you.

 

that guy is lieing to you....
no plug on the block will cause low oil pressure

 

so i found out the problem... and it turned out to be something i didnt excpect.. the waterpump seal/gasket rubber piece popped out of place.. basically wouldnt stay in its place so it was leaking water slowly which caused it to lose power... i didnt figure it out, well of course since i couldnt get it to speed up but i did and the faster i went the more water came out... took it out looked at the seal and it already looked like it was chewed up.. i did buy it brand new too dunno how it turned out like that bu thanks anyways guys!

 

coolant**