full size '90 bronco 302. It starts fine then produces a rough idle, almost dies then recovers without any help on my part, this repeats for a few minutes, any time of day, put into drive/reverse and it wants to quit and sometimes it does. Driving down the road it stalls out, sometimes dies (put in park and restarts just fine), and sometimes recovers and then normal. I am at the end of the rope as far as what I can think of and the end of the money tree. Here is what I have checked (replaced mainly): fuel pump and wiring, fuel filter, egr valve, egr positioning sensor, ignition module on distributor, ignition switch on steering column, stator/pickup coil in distributor, grounds are all new and good on engine, fuel pump, frame, body. rotor and cap are good, fairly new plugs. I'm checking the vacuum lines tonight, other than that . I appreciate all the wisdom and experience you all share.

 

Do you smell fuel? Will it stay running if you give it some gas?

Try...

TPS on throttle body
IAC on throttle body
O2 sensor also

Did you put a lot of that dielectric grease on that TFI Module on the distributor?

 

sounds like iac or vacuum to me.

 

I don't smell fuel and it varies on whether it stays running or not when gas is applied. I didn't use a lot of dielectirc grease on the module, just what came in the little packet with the part. I am currently checking all the vacuum lines and valves,etc. replaced a few that were questionable, cleaned the throttle body thoroughly along with the IAC and TPS. I have attempted to check the readings on these two particular items, but I'm not 100% on whether I'm doing it correctly. My numbers aren't even in the ball park with what they have in the manual no I'm not smoking anything and yeah , da that means they're bad and not working, but like I said I'm not sure if I'm checking them right. No owners manual on the multimeter which doesn't help matters. Take pity on my stupidity at some things

 

Does it do this when it is first started up when cold?

Any check engine codes?

My 1987 truck surges if I start it up when the engine is already hot. I had the same problem on my mustang when it was speed density also. I'm planning on converting my truck to a 302 HO motor and changing the trucks ECM to a A9P mustang computer. I also plan on moving the injector pins since it has a different firing order.

That should give me better gas milage and also help the idle not to mention some power gain from the ho

Dave

 

Hey Dave thanks for the new info. It does this any time of day hot or cold temperature wise or engine temp wise. Will that work- swapping out the ecm between the two vehicles? Although I'm trying to get this running I would like to improve the HP and MPG. Please keep me posted on the outcome. Thanks again