I have a 93 F150 with the 351w (built up, GT40 heads, headers, and a cam for sure, possibly a 408 stroker kit as well) and a 5 speed with overdrive, 4X4. At idle the engine will consistently rise and fall from around 500 to 1000 rpm, and when you step on the gas the throttle will stick at anywhere from 1500 to 2500 rpm. I have a clean IAC sensor (I cleaned that myself) And when I have the engine idling, I can unplug the MAP sensor and the idle will immediately smooth out but it'll idle high at about 1200 rpm. I tried replacing the MAP sensor but same situation arises. I even tried the idle reset thing with the new MAP sensor but still, same deal. I also just recently noticed the EGR valve has been disconnected from the exhaust (plug in the header and EGR end is hanging open) and the vacuum port on the EGR valve has no line on or near it. I popped it off and the surface the EGR bolts to is completely flat, there's no hole for any exhaust gasses to enter if it were hooked up.

 

Has this combination of parts ever worked without a surge? All those parts/mods, I would assume you converted to MAF and had the PCM tuned?

 

I just recently bought the truck. The truck has no MAF sensor, and from what it sounds like it never idled smooth but he did blow out the head gasket and he replaced that himself. After the head gasket swap he created the throttle sticking issue. Thank you for your response btw

 

I ordered a new throttle body, it should be here within a few days. I'll let you guys know what all changes when I get the new throttle body on there

 

The sticking throttle could be a worn TB or a binding throttle cable but it should be easy enough to actually see if either of those parts are the cause of that problem.

If this motor does have all or even most of the upgrades mentioned there is absolutely no way it will ever run well on the original PCM, that combo needs larger injectors and tuning and that pretty much means it also needs a MAF conversion.

 

Okay, thanks for your response. How would I go about the MAF conversion and the tuning job? And what would you recommend for injectors? I was looking for a more performance styled intake/injection, anything out there worth checking into?

 

The new throttle body came sooner than I was expecting so I got the chance to clean it all up (including the IAC sensor again) and throw that on last night. At first it seemed to fix the sticky throttle issue so I went from there and started the process of trying to reset the idle. Left the battery unhooked for about 20-30 minutes came back started it up and left her run at idle for 20-25 minutes, came back and I still have the surging/hunting idle as before. But I also noticed that the throttle is still sticky but only after the engine warms up. Any Ideas?

 

Ford EFI 5 0L 5 8L MAF Conversion Harness Wire Plug | eBay

I found this... Would this be what I should be looking for, for the MAF conversion?

 

You didn't touch the throttle stop screw, did you? It's not an idle set screw, it's there to prevent the throttle blade from binding in the bore. It's pretty common to create a sticky throttle problem if you mess with that screw.

As for the MAF conversion, the easiest way would be to convert the truck to the Mustang A9L/A9P computer.

 

This new throttle body I know hasn't been messed with at all, the old one the previous guy had messed with the stop screw and he had the throttle body butterflies out. That's kind of why I bought the new one.

 

Would a truck computer like this work and be easier? Or would the mustang computer simply just replace the computer I have now?
RARE Ford F150 F 250 F350 E150 E250 E350 Bronco MAF Mass Air Computer ECM PCM | eBay

 

No, that computer will require a complete change out of your harness since it's EEC-V.

Since you have a manual transmission truck, the Mustang computer will be the easiest way to go for you.

 

Disconnect the cable from the throttlebody and verify that it moves in and out smoothly without catching, if not replace it.

 

So would a EEC-IV computer work? I found a truck computer from 94 that came stock MAF

 

Yes you need an EEC 4 computer but that one also controls an auto transmission so it's not suitable in your case... it would throw a ton of code for the missing trans all the time. Best option is a Mustang A9L as it's also guaranteed to be compatible with the tuner you also need.

Did you test out the throttle cable?