I bought a 91 f-150 lariat club cab a couple months ago as a basket case (not running and vague description of symptoms when in failing state) lol. I have replaced the things I have had issues with in my other ford trucks and broncos. The list being: new dizzy, map, egr, egr tube, egr solenoid, vacuum lines timing set, water pump, iac valve, tps, plugs, wires, head gaskets (including surface, pressure, and mag with a fresh valve grind and lap), valve seals and intake gaskets. Set timing by book @ 10 btdc (yes I took the signal plug out when setting lol). Now when I try to read the codes engine off in running position sometimes it will give me codes 34, 82 and 84. It will start with a high idle reaching up to 1400 rpm then calm to 800-1000. Runs smooth for 30 sec- 1.5 min then either hunt or die. When it hunts it throws a serious amount of fuel through the injectors with black smoke out the exhaust. Runs like this for a bit then smoothes out for 30 sec then back to hunt or die. Engine light comes on during this apart and goes off when smooth intermittently. Been twisting wrenches for 18 years and have never had this issue. As of now I just replaced the egr position sensor and have run it same issues but now it won't throw the codes. Am at a loss and running out of cash any help would be appreciated.

 

Found out it is the EEC that is bad pulled it and found the capacitors are fried. Am off to radio shack for parts lol will update when done.

 

Been searching for a replacement EEC for my truck (91 f-150 5.0) and have found that I truely get the oddball vehicles lol. It is year specific and region specific lol. High alt. Cali emissions after a two hour search only 7 in country. eec-IV F1TF-12A650-BBA. So am looking into havering it gone through by a auto electric repair shop in case of the chips or something besides the capacitors are faulty. Replaced them last night and waiting till tonight to test( busy day). Will let know results.