HELP. VL High Idle, running rich???

[88-SERIES200]

Ok so i've got this ongoing problem with my vl running rich and being sluggish until higher revs and its really pissing me off. The cars gone through times of running really good and really really bad whenever something has stuffed up and been replaced. I also have a problem with the engine idling at 1100 - 1200rpm. this is with the idle air valve screw at the rear most of the plenum turned down to the absolute maximum just so it can idle. would be much higher otherwise. im thinking i may have cracked a inlet manifold gasket somewhere when the engine has overheated badly on 2 occasions from a clutch fan and bottom hose failure. with the idle like this the timing was set at between the 4th and 5th marking and is now set at the 5th and still running the same.(98 premium). I have done the following with no change except slightly better idle. swapped dizzy and cleaned points, cleaned every single connection with contact cleaner, swapped TPS, done many injector treatments then changed oil and all filters, swapped many afm's, swapped o2 sensor, plugs, leads, coolant temp sensor, AAC valve swapped,disassembled and cleaned, cleaned throttlbody, new voltage reg on alternator, a couple new hoses to rocker cover, swapped many coilpacks, just put on a newish 2.5 exhaust with lukey mufflers. runs the same as ever and instantly turning new plugs black.



I am suspecting the problem to be somehow related to the following;

Inlet manifold gaskets and vaccum leak elsewhere (for the high idle), TPS, pcv valve?, fuel reg, injectors for the engine running rich. the idle used to be at about 750-800 rpm and the car ran better but still a bit rich and acceleration from 50 to 100 was very fast (for a na). im really hoping this can be fixed and isnt something like valves. any ideas on the best place to start? on last check the computer came back with code 44 no problems..

[Tree cutter]

Check the vacuum hose that goes to your fuel pressure regulator.If it has fallen off your fuel pressure will increase so your engine runs rich. the vacuum leak from having this hose off will increase your idle speed. The hose could be perished so it has a hole in it too