I have a 91 TPI 6 speed, but I have problems trying to make the car proper. When I start the car when it's cold it idles good and the rpms some what jump around 900-1300 rpms when cold. When the car warms up at idle I noticed the rpms go up and down very little(such as the idle ranges from 700-900) and the car sometimes shakes a little when it's idling like that also sometimes WHEN IT'S WARM and when the idle is moving from 700-900 I hear a click sound from the engine ONLY SOMETIMES I don't know what it is and one of the mechanics said it was my driver side CAT and I took the car to a muffler shop and the shop said that the CAT was perfect after they cut it off, and there was no gunk in the pipes. The car feels like its working too hard to maintain a constant speed and the effects I feel from driving the car is that when I gradually give the car gas it feels really sluggish and lack of power and its hard to pass people up without giving it full throttle and when I'm on the freeway it feels super sluggish also the car gets terrible gas mileage I get around 8-13 city 15-18 highway maybe even less then that. I've taken the car to 2 different corvette mechanics and they don't have a clue but so far the parts that have been replaced/checked fuel injection flowed, timing, compression, exhaust, egr valve, throttle position sensor, spark plugs and wires, distributor cap and coil, air cleaner, idle air control valve, maf sensor, fuel filter, O2 sensor, fuel pressure is good, and new fuel pump. After all that the car is still the same I honestly don't know where to go from here but please help and save me!!!:'((((

 

From the list of ceck and/or replaced parts eams they searched in all (right) directions...For your bad idling i suggest to ceck for vacuum leaks,or gaskets leaks.BTW your 91 is a MAP not a MAF car...IF your mechanic talks about a MAF...then change it
Again ,start at very basic:
1 take off the TB and clean it perfectly
2 change intake -plenum-TB gaskets
3 Ceck TPS minimum setting as FSM says
4 Set factory advance at 6 degrees with the ESC connector disconnected
5 ceck ALL vacuum lines for leaks
6 ceck your fuel system lines/filter/regulator and obviously pressure (43 PSI)
7 ceck your injectors using a noid light,and for resistance
Basic stuff...i know,much of these made by your mechanic...but sometimes something eludes