Being a 90' you are NON-I/C, that means you have a better chance at melting something. You have no intercooler to cool your air, you have a baby H1C that doesn't cool as well as other turbos. You also have larger stock injectors to add fuel to the fire. Also with a turned up pump you need to make sure your lift pump can keep up to feed the injection pump, so a fuel PSI gauge is important to. Gauges you need are EGT, fuel PSI, and boost. With a auto trans a trans temp gauge would be a good investment also. Gauges can get pricey easy, some can run almost $200 for one gauge. This gauge has lasted me over 2 years now GlowShift | 3 in 1 Multi Diesel Gauge - Boost, Pyrometer EGT, Pressure Diesel Gauges
They are cheap compared to other sets, and some have trouble with them but mine has worked great. This link has some awesome info for any 1st genner, and has everything from basic maintenance to performance FAQ/Knowledge base "How do I...?" Look here first! A.K.A. "The Sticky" - Dodge Diesel - Diesel Truck Resource Forums
Read through it and you should find out alot of good info on how to get more power, and fix alot of issues you come across. Good luck.