I have a 1994 5.0 with a terrible idle problem. Sometime it idles just fine and then sometimes the idle will go from 500 to 1500 rpm and eventually die. From what I have read this is a common problem when the motor is modded. Here is whats been done:
AFR 165 60CC heads
E303 cam
1.7 roller rockers
BBK long tube headers
75 MM promass air
24lb injectors
70 MM throttle body
Professional Products Typhoon upper and lower intake
The previous owner said something about tuning the "Exhaust Phase Timing" because of O2sensor being further away because ofthe long tube headers.
Also mentioned he had to replace the O2 sensors quite a bit because of the headers.
Any help or direction would be appreciated.
Thanks

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i would first replace the throttle position sensor its not that expensive and maybe something is wrong with your mass air flow sensor?

 

Has the car been actually tuned on a dyno yet? If not, no wonder it runs like ****.

 

Its been tuned on a dyno.

 

Could be you iac (idle air control valve) or vaccum leak, what is it timed at? sounds like your timing may be off, and have you added anything after the dyno tune?

 

kennebellgt is more than likley spot on. Every Ford that comes into our shop that has an IAC and has an idleing problem gets that thing taken off and cleaned. I yank them off and clean them with throttle body cleaner and also clean the port that it goes in the same way. If you have any of those engine brushes, run that through and around each part also.

 

Thanks for the help it gives me a direction to go, appreciate it.