Good deal.
I had a coworker who did an EFI conversion on his mustang. Ran great, for about 30 minutes at a time, then started running lean and eventually died. A few hours later it would be fine, but do it all over again. It was a head scratcher for weeks, I think he replaced the fuel pump a couple of times, diagnosed wiring connections, ran the thing on jackstands until it got hot enough to see if something was changing when warm, rerouted his fuel lines to keep them away from the exhaust, and a bunch of other stuff. Turns out his tank vent wasn't right and it was pulling vacuum as fuel was removed, causing it to lean out from low fuel pressure. Since then I always keep an eye out for things like that.
