car surges when I let off the gas

[92stanglx]

My car idles fine and drives fine with no surging. However, when I let off the gas and let the car coast it starts to surge. When I step on the gas again it stops.

What could be causing this? Here's my combo:

'92 LX
331 w/ H/C/I
Vortech S-trim 6lbs of boost
UPR power pipe
SCT MAF
SCT custom tune
full exhaust
42lb injectors.

[speedytang]

If you don't have a BOV install one to correct the problem and if you have a BOV verify that it is working.

[92stanglx]

If you don't have a BOV install one to correct the problem and if you have a BOV verify that it is working.

I'm using the Bosh bypass valve. How can I tell if it is working?

[speedytang]

Make sure it is holding open when you apply vacuum to it and it does not leak off. You need a hand vacuum pump and watch the gauge and see if it starts leaking off and closing. If it closes then it is going up and down and causing your surge feeling. If you have a wideband you can verify that it is not metering and O2 issues causing the surge. If you have a fuel pressure gauge you can make sure that your fuel pump or fuel regulator is not going bad.