Hi all,
I've been trying to figure out this truck. I'v got an 85 F-150, 302 FI. It starts up fine most all the time, idles high for at least a full minute then idles down to where it should be. Just as i touch the gas it stumbles and sputters but if you keep pushing the gas it goes fine. It will surge sometimes and if your in traffic and just hit the gas and let off it willrev up and drop dow so low it will die sometimes. It starts right back up usually just fine. I ran the codes and got code 41, from what i have read it is system lean, no switching detected. I have already replaced the TPS, IAC, O2, plugs, wires, cap, fuel filter, air filter, PCV, cleaned the EGR, tested the EVP sensor with a multi-meter, swapped the map sensor from my other truck, all with no change. I was getting other codes in the past before I changed out some of the sensors but the code 41 is still here. I disconnected & plugged the vacuum from the fuel pressure regulator, no difference, same with vac to EGR, no change. There'sno schrade valve that I can find to test fuel pressure and no fuel was leaking out of the vac line of the regulator so I don't think its bad. Does anyone have any ideas what this could be. It's like whenyou take off it sputters like is running out of gas but you get on it and it goes fine, floor it and goes with plenty of power. Thanks

 

Sounds like a vacuum leak, if the juice can is still there check it for leaks they all rust out eventually.

 

It doesn't have a "can", all i found is a plastic square thing behind the battery that the vac goes to and comes out of going to the vac switches directly behind it before they go to there devices. I'll look again for leaks