I installed my new fuel sytem and EZ EFI about 6 months ago. I've had other engine issues in the interim but have that all ironed out and am focusing now on fine tuning. This is a 64 TBird with a rebuilt 390. Decked, balanced. Lunati hydraulic roller cam and lifter set, mild lift and duration for best idle and low end torque. Compression ratio is 9.7:1 and I use premium gas. PQ adjustable roller rockers. My goal is smooth operation, easy starts, good fuel economy. The engine starts a little hard when cold, a little worse when warm. Idle is good but not perfect. Power is good. No knocks at all. The biggest problem is that cruising power is not smooth. It feels like an ignition issue but I have done everything that I could to tune that. My best description is that it feels like one or more of the cylinders are not firing completely. Fuel mileage is terrible- around 8 or 9 and I should get around 16. The ignition is a FAST E6/ E92 with a new Pertronix distributor. Ignition timing is 16 BTDC initial, increases to 34 between 1500-3400 RPM. I have the vacuum advance connected to the throttle body above the throttle plates. I double-checked all the E6 wiring so that it is exactly per the instructions. Large red directly to the battery- no fuse. Large black directly to the block ground. FAST recommends consider grounding both heads to the block, and I have all ARP engine bolts so was concerned about this, but I measure zero resistance between the block and heads. Spark plugs are Autocraft copper, brand new, gap set to 0.039. Wires are MSD Street Fire. Note- Earlier I had a set of Autolite plugs and Taylor Street Thunder wires and the car ran terrible. The wire boots were too long on the plugs and it was difficult to get a "snap" when installing. I trimmed the length of the boots and that made the assembly only marginally better. After a 100 mile run I found #8 plug black and #3 broken insulator. I gave up on that combination completely for the Autocraft / MSD combination and the connector fit to the plugs are much better. I also double checked the wiring on the EZ EFI 1.0. Red is to the battery + post, fused. Black to the battery - post. My fuel system consists of a Tanks Inc pump inside the gas tank. Tank is vented. I have an Aeromotive AFS 12308 filter and AFS 13129 bypass pressure regulator set at 43 psi. 3/8" steel supply and 1/4" steel return. Hose connections are all 3/8" Russell hose and AN connectors. When I turn the engine off the fuel pressure immediately leaks down to zero. I suspected that I might have some crud keeping an injector open so I replaced all four. When I did, I inspected the fittings in the throttle body carefully and found that the casting was porous. I'm not sure if this is the problem or not- I suspect not. Pictures of each 4 are attached.