Getting code 45 and engine sometimes dies when let off gas

[vstarsilverado]

I recently bought an 87 GN that was dying for gas- it would stumble all over the place under just minimum boost. It had some nice goodies, but wasn't any faster than stock (probably slower) and I thought something simple was holding it back. Turns out, it had an old stock fuel pump in it and was also pumping through a disconnected booster pump (I have no idea why). I had it replaced with a Walbro? by a mechanic I trust and he put in a new fuel filter and upgraded the fuel pump wiring. He also put a new fuel regulator on it, replaced the vacuum lines, changed the plugs, put in a new high perf. air cleaner (had a stock unit), created an adjustable turbo waste gate, and boosted the pressure from the lousy 9 lbs the previous owner had it set on, to 15 lbs, and a larger inflow pipe going into the turbo unit. It already had a larger turbo on it, 38 lb injectors, a Kenne Bell torque convertor, a Kenne Bell Ultimate Chip, aftermarket headers/exhaust, and a Kenne Bell 70 mm throttle body.

Anyways, the GN is now a blast to drive- it accelerates great under boost and isn't starved for gas when kicked in. It sure seems like he took close to a couple of seconds off the 1/4 mile. Everything works fine, except now when I let off on the gas to cruise to a stop, the engine often dies, which is kind of dangerous when entering into a corner and losing all power. And, ever since I got it back, it's pulling a code 45 for rich fuel- the only error code it has. It didn't have that code before this work.

Any ideas? I'm going to take it back to the mechanic but I'd like to know what to ask him to focus on.

Thanks.

 

[scgnx]

Kenne Bell everything car...well a good possiblity is the IAC valve being out of adjustment. I would loose that chip and get one burned for those injectors and combo. Did you get an adjustable fuel regulator ? If not get one, it helps tune. Also, invest in a scan tool. They can really help sort out problems.

Good luck