Hello, new to the forum -- Need some help with a troubled XJ

2000 Cherokee 4.0 -- 225,000 miles

Jeep starts but misses terribly -- Barely runs at idle -- runs when on throttle but very rough, misfires badly

When I bought it it needed the dual cats at the manifold -- cali emissions

bought the walker setup, re-welded all the joints, and installed all new O2 sensors because I didn't have 2 of them

So now that it's quiet The jeep is misfiring badly -- Changed plugs to champions, tested Ignition coil pack -- All Coils OHM out equally -- then tested spark with a steel brake line connected to ground -- All coils firing strong

After plugs I started getting codes -- One was injectors -- open circuit cylinders 2 and 4 -- I tested the wiring with no real results -- could never get a reading on my Volt meter -- I changed injectors -- upgraded to the ford mustang ones

Now with new injectors the injector codes are gone -- New code -- P0122 -- Throttle Position Sensor Low voltage

In an attempt to diagnose the TPS -- The 2 outside terminals on the plug 5 volts in and ground -- the center terminal on the plug is supposed to be TPS signal out -- I get 4.32 volts there with the TPS unplugged from the wiring harness

4.32 volts -- Only hooked up the the PCM -- Now I search wiring diagrams and find which pin is connected to TPS input on the PCM -- Pin #23 -- With the PCM wiring harness unplugged I get 6 volts on PIN # 23 -- I also get 7 volts on the pin which is supposed to be 5 volts to power the TPS -- I forget the pin number

So now what? -- Is my PCM fried? I don't even know where to look now...


Thanks for your thoughts -- hope you can understand this

Jer