PROBLEM:

My 92 F150 Nite is sick....runs fine in park, but when I put it into drive or reverse the tach drops significanlty and acts like it whats to die and some time it does. Also when I'm at a stop light and let off the brake it "studders" and also sometimes dies. I've also noticed that when I'm on an incline it does the same thing.

Corrective Action Taken:

Replace the spark plugs, wires, fuel filter, PCV Valve, EGR Sensor, Idle Control Valve, Sea Foamed the Injectors, Clean Throttle Body, replaced the Cat, check the timing and none of this seems to haved corrected the problem. There are no lights on, took it to Autozone with no codes (I then found out that the light must be on in order to pull a code, DUHHHH!)

At the end of my rope not sure what else to due!!! replace the EGR Vavle (not sure how to check if it's bad), O2 Sensor?, Throttle Body Sensor?, Fuel Pump?, low line fuel pressure, or just Burn it in the yard on the 4th!!!!

Any advice would be greatly appreciated.

 

I had this same problem with my '93. I spent a lot of money replacing the same stuff you have and was about to give up. Long story short, turned out to be a hair line crack in the driver's side motor mount!

 

Just wondering why a motor mount would cause the problems that I have? Also how can you tell if it has a hair line crack? I'm just guessing that I could have to inspect them.

Sorry for sounding stupid just at witts end here, anyway thanks for your insight into the problem.

 

The motor mount is a long shot for your problem, but it doesn't cost anything to take a look.

I have no idea why a cracked mount on my '93 made the engine spit, sputter, shake and die when at an idle and in gear. Two dealers and three smaller repair shops never found the problem. A friend decided it was my plugs, and changed them out (that would be the forth time someone was positive my plugs were bad for this problem and replaced them with their pet brand. I had already tuned it up myself, but no one trusts anyone to tune up an engine correctly and they'll never like whatever plugs you used). He dropped a socket when changing a plug and it fell right on top of the cracked mount. Needless to say, replacing the mount fixed the problem.

 

^^^^^
Are you sure it was the mount and not the exhaust manifold?