My 90 f150 5.8 I bought to restore was idleing erratic when cold and would rev a little high at OP. Temp, so I checked the codes and got a 98(hard fault pcm in back up) and a cod 63( TP sensor signal below minimal ,possible short). Looked under the hood and the TPS was diconnected so I plugged it back in reset the pcm and code 98 went away and instead of code 63 I got code 53( TPS signal above maximum limit,possible open) . After that I let it get to op temp and the damn thing revved to 3000 rpm and stayed), now I know why the tps was unplugged , but my question is since I dont think this model tps is adjustable, is my tps shot or could I fix by adjusting my base idle? Or clean the tps, also it does look like its pointing towards the iac. Anyone ever have this prob. I know I should test it but my multimeter recently died on me. SN. Before the koeo test I shot some starting fluid by my upper intake and it revved up so I know my intake is probably the cause of my erratic idle. Can my intak leak mess with the TPS. Sorry for my long and confusing question but I'm a little irritated my truck has been such a pain in the ***. Thanks for listening though guys.

 

I mean the harness is pointing away from the iac

 

Replace it $40 at auto zone...worked for me...I tried cleaning it didn't work...its not adjustable.

 

Just looked in my haynes and 90 and earlier models are adjustable. Gonna try to adjust but I don't think you can adjust them in large increments, so most likely its bad.