I have an f150 with 460 engine out of a 71 Lincoln. My problem is when I'm driving the truck will start to spit and sputter and run rough when it does this I lose all power on the gas pedal it just drops to an idle and if I step on gas to try and wake it up I get nothing. Sometimes I can downshift and it will come out of it, and sometimes I have to put in neutral before the pedal comes back. It done this a couple times before but got worse after I changed plugs and wires. Double check wires and everything is right. Also when I start it the idle gradually gets higher and higher.

 

You only did a part tune up.
What is the cap & rotor like?
Air & fuel filters new or old?
Did you check timing or adjudt the carb?
Have you replaced all the rubber fuel lines from tank to carb? One could be bad and causing fuel not to get to the carb.
Bad fuel cap not venting could be a cause.
Just to name a few things.
Dave - - - -

 

Rotor looked fine, cap had some build up on it but I cleaned it up. No way of checking timing. Runs fine but after I drive it for a little bit is when it starts. Acts like it might be a vacuum problem. I guess it could be a bad line. Maybe the vacuum advance or coil? I really have no clue.

 

FuzzFace2 suggested, "Bad fuel cap not venting could be a cause."

The next time the sputtering happens, loosen the fuel cap and see if the problem goes away.

 

No time usually happens as I'm driving last night it was doing it when I was camping down the lane pulling in driveway but it wouldn't stay running long enough to try that

 

Try loosening the cap before driving and see if it sputters.

 

I'll try but cap and neck looks new

 

I drive about 10 minutes to work and runs fine then when I get about a mile or 2 away it starts to miss and usually if I put in neutral and accelerate it usually comes out of it but last night in the driveway I couldn't even keep it running without giving it gas and even then it was running rough

 

If I had your address, I could send you a new cap and rotor. Do yourself a huge favor and finish the tuneup before blindly throwing parts at the poor engine. I’d even suggest new plugs and plug wires.

You mentioned you have no way to check the timing. Beg, borrow, or steal a timing light. Right now the situation is like a doctor without a stethoscope.

Test the fuel pump for pressure AND volume. You’ll need an inexpensive pressure gauge. Maybe $20. No whining if you don’t have a gauge and timing light. Some auto parts stores will loan them for free.

Those are just some basic diagnostic steps to take before digging elsewhere too deeply. In the immortal words of Douglass Adams: “Don’t panic!” Rule out the easy stuff first.

 

Big clue right there. A minor problem turned into a big one immediately after some work under the hood. No assuming parts are good because they are new. Plug wires, especially cheap ones, can easily break internally during installation. I’ve had new wires fail within a couple of days of installation.

 

I was going to say that about the fuel cap. Just remove it before the next drive. No money spent
and it is easy to do.
May want to replace all the rubber fuel lines. They go bad from the inside out and can not see they are bad.
Dave ----