[kilgorq]

When you say not instumentation are you refering to no lights on the dash at all or just no rpm gauge response. If you are referring to a dead dash at the same time at the running issue then look for a bad ground either under the dash or the ground between the engine and chassis. It sounds like your computer is getting dirty power (Low Voltage). Also check the voltage at the battery before you start it and after... You may just have a weak battery that is not putting out enough voltage to run the field in the alternator so you entire electrical system is trying to run on low voltage (11 or less). You should get about 12v before you start and between 13.5 and 15 when it is running. If the voltage looks good go for battery terminal connection and then the chassis-engine grounding .