Run a computer diagnostic test first, it might just be a minor electronic component malfunction. It could be something as simple as an EGR valve or even deposits on the EGR valve assembly, but you can't guess at something like that.
The #1 cause of hard starting a 1991 ford explorer is having lost your keys
The A4LD transmission is the weakest part of the 91-94 explorer. It is likely that your transmission has failed.
clutch plates could be welded to gather
Water in the fuel will keep it from starting.
Trouble code P1504 means: Idle air control (IAC) circuit malfunction
It's definitely a transmission problem. Any further analysis will require a bit of hands-on work to determine the cause.
a bad brake caliper or pad.
It COULD, but more likely it would just cause it to run poorly once it starts.
I don't know about the Explorer but I had an experience with a Ford Mustang. I changed about everything I could think of related to the non-starting problem. Then I discovered there was a filter in the gas tank. Changed it and the problem disappeared!
bullie cause trouble.
Bad bulbs can be the cause of your reverse lights not working on your 1999 Toyota Tacoma. A problem with the reverse switch or bad wires can also be the cause of your reverse lights not working.
Trouble code P2104 means: Throttle actuator control (TAC) system-forced idle mode Trouble code P2112 means: Throttle actuator control (TAC) system actuator stuck closed