car- 91 civic sedan 5 speed. (isnt my car, im just doing all of the work on it)

d16z6 swap. converted to mpfi and obd1 with a p28 ecu (i have don this on like 10 other cars and never had a problem) all conections are soldered and shrink tubed (i hate tape)

issue- the car runs good when cold, but once it comes to temp, it barely wants to hold idle. it idles quite low, and choppy. it doesn't have a miss on any single cylinder. it simply sounds like a crotch rocket idling. it don't idle surge. it usually tries idleing around 4-500 rpm once warm. the real problem is that it has a bad hesitation, and bogs when under 3,000 rpm, even when driving at steady throttle/ speed. if you give more throttle, it simply bogs and studders until full throttle is reached, or you back back out of the throttle. if i give the car a vacuum leak, it idles at the proper rpm, but its still very choppy. once over 3,000 rpm, it runs great, and really pulls hard (for a single cam) it has an audiable and feelable vtec crossover which is kind of odd considering its a z6.

the car got a new dizzy when i did the conversion along with new cap and rotor button. also new 4 wire o2 sensor as well. so far, i have tried known good tps, map, and ect sensors as well as iacv, a different throttle body, different plug wires, plugs, gone back over the wiring multiple times, checked the charcoal canister, as well as check for any vacuum leaks. also tried a different dizzy, different ecu, and even checked the connections at all plugs. it has good fuel pressure, strong spark, and good compression. timing is set to 16 degrees base, and cam timing is spot on.

i would really appreciate any in site into anything i could be missing, or any other helpful information to figuring out this issue. it has me stumped.

 

wow, make a thread where people cant complain about lack of information, and then no one says a thing lol.

ok today i found a very slight im gasket leak, i replaced the gasket and it didnt fix the problem. i made sure to bleed the cooling system afterwards. tried a different set of injectors, and that didnt fix it, unbolted the exhaust at the header to rule out and obstructions in it (owner said his friend swore it was a bad cat), and no change in the way it runs. checked all valve clearances, and they are in spec. it has been consistently throwing an o2 code, but now its not throwing it, and instead throwing the dreaded 43, fuel supply system. i have tried unpluging the o2 and running the car with it unpluged, and that dont change the way it runs either.

im ready to tell him to put full coverage on it and find a big oak tree. to make matters worse, the owners truck blew up today, so now he is rushing me to get it figured out so he has a vehicle to drive.

 

more info. if i unplug the iacv, the car completely dies, even with the idle screw backed way out. unplug map, it dies, unplug tps, it runs worse. i have cleaned all of the passages in the tb to make sure air flow is good. its just kind of odd that this thing wants so much air to hold a good idle. usually giving a honda a vac leak will cause it to idle high like around 1500 rpm, but it just makes this one idle where its supposed to be. any ideas?

 

fuel pressure is good. tried known good fpr also, and new fuel filter. so far, no change at all. i give up. thanks for nothing h-t