Starting and Stalling 1988 4-cyl Convt.

[ziggy555]

I have a 1988 Mustang 2.3 Cyl Convertible and I have recently tuned it up replacing the plugs, cap and rotor. About a month later the could turns over but will not start, but eventually does.
When driving the car at random times, the tach will be between 1-3 just rolling along and then it cuts out and drops to 0 and goes back and forth up/down and has stalled as I come to a stop.
I then replaced the fuel filter, same problem. I then replaced the fuel pump regulator under the drivers seat, same problem. I have tried super unleaded with a dry gas additive, same problem. I am thinking its either a spark/ignition or fuel problem? If you have had a similiar problem or have any suggestions that would be great as I am now afraid to take long drives until I resolve this problem... Thanks to all who respond.

Ziggy