Hi & welcome to TVT! The intermittent no start problem, assuming you mean the starter will not activate, is a fairly common issue on these. This can be one failing part, or the combination of slight losses from multiple electrical components and/or connections. The most common single part is a worn contact inside the starter. For more information on this,
HERE is a good thread that explains. I would recommend anybody having this problem open their starter and inspect/replace contacts before doing anything else.
The next most common cause is failing contacts inside the ignition switch (in the steering column). To clarify, this is not the part you put the key into (that part is called the ignition lock/cylinder), it's the electrical component driven/rotated by the cylinder (under the panel on the other side of the column). I have replaced the ignition switch before on different vans with varied success, but the last time I ran into this replacing the ignition switch only reduced the frequency. I eventually cured the problem by installing a Bosch relay in the engine compartment down by the starter. I rigged it so the signal from the ignition switch activates the relay (instead of the starter solenoid) and the relay then activates the solenoid by switching + power directly from the battery to the starter solenoid. I would recommend 12 gauge wire from the battery to the relay and from the relay to the solenoid.
A relay here is basically a band-aid. Assuming your problem is the result of small electrical losses from multiple components/connections, these losses are directly proportional to load. Lets say your starter solenoid needs a minimum of 10.5 volts to activate (this is a reasonable expectation). Lets also say the battery voltage is about 12.5 volts (this is typical of a fully charged battery). When you take into account the the "barely adequate" wire that Toyota uses in the circuit, I think it's reasonable to expect ~1 volt drop through it (while under load).........now you're down to 11.5 V. If your ignition switch contacts lose another 1/2 volt, now you're down to ~11 volts. When you consider the neutral safety switch and various other connection points (each with small losses) it's easy to understand how this can become an issue. If this (low voltage to the starter solenoid) is the culprit, a relay can remedy this because it will significantly reduce load (smaller load = smaller voltage drop). A weak circuit barely capable of engaging a starter solenoid could easily engage a small Bosch relay. The relay can then be used to deliver full battery voltage directly to the starter solenoid. If this is too technical, print it out and take it to your mechanic (he'll understand).
Regarding your key coming out of the cylinder with the van running, this is also a common issue (but unrelated to your start issue). Toyota's ignition cylinders are weak. Years of wear typically result in this problem. The other thing is security. Lock cylinders that allow a key to be removed while running will usually also allow the van to be started with different keys or even a screwdriver. For security reasons, people with this issue should either replace the ignition cylinder and/or install a hidden kill switch. Don't make it easy for thieves to steal your van. We have members here (at least 2 or 3 per year) who lose their vans due to theft.
Last time I checked you could still get a new cylinder (with 2 keys) for around $100 (try one of those discount Toyota parts websites like
1stToyotaParts.com). The part number is 69057-28021. A new antenna is Toyota part #86300-28010 & sells for around $50 on one of those sites (if it's still available). Tim