fuel system problems??? HELP

[asd_gst]

ok i have a 91 gst with stock fuel system, the car has a bcs removal, k&n air filter, and hacked air can, sometimes when i turn the car on it seems like its missing or not running on all cylinders it will backfire a little then shut off(not a loud just like a little poof sound) then it will stall, but if i rev it up it will run as long as im givign it gas but seems to be running lean or missing, other times when its doing this it wont even start, then other times it starts up and runs fine, but the idle will be going up and down for a few minutes then it get a normal idle and runs perfect, and aslo when driving in any gear after 4000rpm the car seems not to be getting enough fuel or something, like its boosting but doesnt want to go anywhere and seems to bog down. i have posted threads like this before in the newbie forum but never really got a good answer to why its doing this

 

[TSi_with_psi]

Have you done a boost leak test? Also, are you running NGK BPR6ES's plugs with a gap of .028"-.032"? Is your check engine light on? if so, what are the codes? just trying to get a bit more background information. One thing that would cause your car to lean out is if your MAF sensor gets dirty. You can spray it out with some electrical parts cleaner if its dirty. If your fuel filter was clogged or the filter sock on the pump was clogged you could lean out as well, however i dont think your problem is a clogged fuel system because that would not cause intermittant starting. big vacuum or boost leaks can cause the car to run lean under vacuum and rich under boost, it just depends on where the leaks are located. But vacuum or boost leaks would have to be extremely severe to cause the problems you are decribing, and they wouldnt be intermittant. Have you checked the electrical connections to you Coolant temp sensors? they will also have a significant affect on the AFR's.

 

[erald01]

Well i would check a few things just to be sure: 1) check your fuel pump and make sure its not going bad, that will cause a fuel cut. 2) check your injectors, unplug them one at a time while the car is running and see which one has gone bad(if thats the case). 3) check your plugs and wires 4) swap yout fuel regulator with a new or functional one and see if it makes the difference. 5) check for a major boost leak, such as your intercooler couplers or throttle buddy. Thats all i can think of right now but keep looking because you know how these cars are, anything is possible

 

[asd_gst]

Have you done a boost leak test? Also, are you running NGK BPR6ES's plugs with a gap of .028"-.032"? Is your check engine light on? if so, what are the codes? just trying to get a bit more background information. One thing that would cause your car to lean out is if your MAF sensor gets dirty. You can spray it out with some electrical parts cleaner if its dirty. If your fuel filter was clogged or the filter sock on the pump was clogged you could lean out as well, however i dont think your problem is a clogged fuel system because that would not cause intermittant starting. big vacuum or boost leaks can cause the car to run lean under vacuum and rich under boost, it just depends on where the leaks are located. But vacuum or boost leaks would have to be extremely severe to cause the problems you are decribing, and they wouldnt be intermittant. Have you checked the electrical connections to you Coolant temp sensors? they will also have a significant affect on the AFR's.

no engine lights are on

 

[asd_gst]

http://www.dsmtuners.com/forums/tuning-engine-management/293387-ecu-leaking.html look at this