98Ford 150 4x4 4.6L / my truck was falling on its face whenever I gave it gas so I replaced fuel filter. same. I bought obd2 1000 code reader ect and figured I better change plugs n wires n oil filter. Did that. The old plugs were extreamly corroded and hard to remove. And it runs worse now! Starts up great but as soon as it warms up it's UNDRIVEABLE. Falls on its face totally. Cleaned MAF sensor w cleaner.. Changed o2 sensors bank 1 n 2 pre cat .Cleaned back o2 sensors. Changed ignition switch. Nothing! F.Y.I. the instrument cluster is shorting out . Gauges do what they want and the rpms are going up n down w the movement of the gauges. Also when I put gas in it goes into the ground and it's not full at all. I'm a female w noone to help me. I live in the mountains so I need my truck to survive .I have a broken leg and neck. And I spent all my money on parts already. Someone please help me. Please!

 

Did it run well before? Has it ever run well? How many miles?

Are you saying that there is a hole in the gas tank, or that the gas just disappears quickly? Might be that you have a leak after the fuel pump and aren't generating fuel pressure, which causes your running problems, and the fuel is being pumped out.

Fix the simple stuff first, like the fuel leak.

 

Yes it used to run ok. When I put gas in if I go reAly slow it's ok. But it goes on the ground if I pump normaly. And a guy put a reader on it and said when I have the gas cap on it has less pressure then if it's off.?? And when the plugs were changed it ran way worse.

 

Just a wild guess, for a clue, try running it with the cap off.

The fact that it runs worse after the plug change suggests that somebody made a mistake when they changed the plugs. Firing order, or damaged the plug wires.

 

I'll check the firing order and I tried w out the cap . It didn't work. Thank u very much for your time.

 

How important is forking the plugs down? I'm not sure if that was done right. I put new wires.

 

If you mean torqueing the spark plugs, not too important. You do not want to overtighten as the threads are easy to strip in the head and you will have worse issues. I snug them up with a 3/8" socket with an extension and call it a day. But I use a smidge of anti-seize which is a no-no when torqueing to specs as the lubrication can make it too easy to blow by the specs with the wrench not clicking. Hoping that you blew out the spark plug holes with air before removing them as you mentioned they were badly corroded. Hopefully debris did not fall down into the cylinders when you removed them. What color was the old spark plug electrodes? Black and sooty, tan for normal, or white for hot and lean? Was a cylinder compression done to see if all the cylinders are reasonably close to each other?
BUT!!!, lets get back to basics. You need fuel and as BareBonesXL noted, get the gas leak taken care of first. Would hate to see your ride go up in flames. Otherwise I was wondering about the fuel evaporator crap being saturated and causing a vacuum issue for the fuel supply. That will not cause a leak though. Has the fuel filter been changed? You might find that the whole fuel line is badly corroded and rotten, or it is just a leaking fuel pump. Ford had awful luck with electric fuel pumps in the 80's and early 90's.