I recently got done with a full resto on my 94 complete with engine swap. The 'new' 460 came out of a 91 with an rv cam and .030 over. I put on headers and took off the PCV and smog pump. Just after the swap it ran fine for about 2 weeks. Then it started acting off sometimes and it got worse and worse until it was a missing and spitting mess. Took it to a shop to get it diagnosed and ended up with a new distributor and ecu. This fixed the problem... for a while. Now its at a point where it will run all day some days, sometimes it won't start, other times it will die while running, sometimes coming back on quickly (its a manual), and other times needing to be left on the shoulder to think about whats its done for a while. While it runs, it runs fine, aside from an idle drop occasionally.

Things we've checked or replaced:
Distributor, cap, rotor, wires, plugs
ECU
Fuel pressure

Things I've considered but haven't ponyed up for:
MAP Sensor
Coil
Better distributor (I've heard nasty rumors about bad pip sensors in rebuilds)

Let me know what you think. I put 10k into it this summer and would like to be able to show it off again as soon as possible. Thanks.

 

Have you replaced the TFI module? It's either bolted to the distributor, or to a heatsink on the drivers side fender.