A few things i learned with my 1992 C4
-Brakes are expensive,i replaced all four rotors and pads which cost close to $800 just for the parts.
-The LT1 engine uses a optispark distributor system,it WILL cause trouble at one point,i replaced mine with a billet msd unit which works great.Replace your water pump at the same time as doing the distributor job,since its right above the dist and needs to come out anyway.
-PASSKEY keys are very $$ to replace if you lose them!all C4's have them.
-They rattle,92+ were the best so i've been told
-Other than that i have found mine to be a very reliable ride,and easy to maintain,i took a trip out to Spokane Washington last season without a single issue and averaged 25mpg on the highway.
Good luck with your search and wecome to the forums!