'91 4.0l will have a MAF(mass air flow) sensor, this is the main sensor to determine fuel mix.
TPS sensor is for quicker response time, like the accelerator pump did on a carb.
You didn't described your symptoms, so just shooting blind here.
If MAF has been cleaned then it could be low fuel pressure or clogged exhaust.
Fuel rail should have 35psi of pressure, more than a tire's pressure.
Usually with clogged exhaust it will start and idle OK but stall out when trying to increase RPMs, low fuel pressure is almost the same symptom.
Bad TPS shouldn't cause a no start, and check engine light(CEL) will come on.
Computer doesn't use many sensors to start and idle.
MAF, IAC(idle air control) valve and ECT(engine coolant temp) sensor are about it.
ECT is a 2 wire temp sensor that only the computer uses, it is like the Choke for fuel injection, if ECT shows cold computer runs engine richer with higher idle(IAC Valve opens more)
Spark on the '91 4.0l is self contained, it uses a EDIS-6 module(on rad support) and a coil pack, these rarely fail, EDIS module does send timing pulses to computer to sync fuel injection with spark, but no pulses would = no start, not hard start.